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This study was conducted to evaluate the relationship between leaf iron and some easilyavailable soil properties in citrus orchards in the southern region of Kerman province by artificial neural network modeling and stepwise regression. For this purpose, 40 orchards were selected from the study area and the physical and chemical properties of soil and iron in the plant leaves were measured. Using artificial neural network in different models with different data from soil properties as input and leaf iron as output, the ability of these models to predict leaf iron concentration was evaluated. The results showed artificial neural network with variables of organic carbon, pH, clay, phosphorus, TNV and electrical conductivity with explanation coefficient of 0.86 and 0.81 and root mean square error (RMSE) of 14.60 and 20.13 mg.kg-1 for data Training and testing were the best models in estimating leaf iron. Comparison of regression and neural network models in the test data showed that the neural network had a higher accuracy with an explanation coefficient of 0.81 than stepwise regression with an explanation coefficient of 0.2. The amount of RMSE in the neural network also improved and increased from 27.72 mg.kg-1 in the stepwise regression model to 20.13 mg.kg1 in the neural network. Artificial neural networks have been able to predict the iron in plant leaves based on the easily-available properties of the soil, so that by choosing organic carbon as the input of the first model to the best model by selecting organic carbon, pH, clay, phosphorus, TNV and electrical conductivity, model accuracy increased. [ABSTRACT FROM AUTHOR]

1- Introduction Water erosion is the result of interactions between various environmental factors such as topography, soil characteristics, climate characteristics, runoff and land use and management. Sediment production is highly dependent on runoff, so doubling the speed of runoff increases its leaching capacity and transportability up to five and six times. Knowing the effective factors in sediment production plays an important role in determining the amount of sedimentation of a watershed and understanding the phenomenon of erosion and its consequences, and it can be used in prioritizing the sub-basins of a watershed. The purpose of this research is to investigate the relationship between morphological characteristics and the amount of sediment production in the catchment area of the Gharasu River in Ardabil using principal component analysis and multivariate regression, in this regard, using 16 independent variables and 1 dependent variable in 13 sub-basins of the Gharasu River. 2- Methodology As one of the sub-basins of the Aras catchment basin, Gharasu catchment is located in the geographical coordinates of 47°31' to 48°47' east longitude and 37°47' to 38°52' north latitude. In this study, 1:100,000 scale geological maps, 1:25,000 scale topographic maps, and discharge and suspended sediment statistics and information of 13 hydrometric stations of Gharasu River sub-basin were used in the 50-year period from 1350 to 1399. In order to check the correlation between independent and dependent variables and to test the normality and normal distribution of data, Shapiro-Wilk and Kolmogorov-Smirnov tests were used in SPSS software. Also, in this research, the OLI Landsat 8 satellite images were used to extract the vegetation cover index (NDVI). For this purpose, step-by-step linear regression is used to determine the most effective variables and to determine the most appropriate statistical relationship between suspended sedimentation and the variables used, and principal component analysis is used to determine the most effective factors of suspended sediment production in the watershed. 3- Results In this study, the average annual suspended sediment of the basin was considered as dependent variable and other parameters as independent variables, and Pearson correlation method was used to check the correlation between independent variables and dependent variable. The variables of time of concentration, length of the main waterway, area, Slenderness ratio, perimeter and slope have a higher correlation with the amount of sediment production in the basin than other variables. Based on the models obtained from sediment correlation analysis, the amount of sediment produced with the concentration time variable had a positive correlation and was significant at the 5% level. The results of the analysis of the principal components show that the four factors of area, length of the main waterway, concentration time and slenderness ratio of the basin have an eigenvalue greater than 1, and the number of extracted factors is 4 factors. The first factor (area) has been able to explain 37.230 percent of the variance of all research variables. This value is 24.735, 16.950 and 9.849 percent for the second factor (length of the main waterway), the third factor (concentration time) and the fourth factor (slenderness ratio) respectively. 4- Discussion & Conclusions The present research was conducted with the aim of investigating the relationship between geomorphic parameters, vegetation and erodible formations of selected sub-basins of Gharasu basin with the average annual sediment. For this purpose, the statistics and information of 17 variables (16 independent variables and 1 dependent variable) were obtained for 13 sub-basins of Gharasu basin from the regional water of Ardabil province. The relationship between geomorphic parameters and annual precipitation was determined using stepwise multivariate regression method. The research results indicate that geomorphic parameters have a high correlation with the amount of annual sediment production and can be used in sediment prediction. Meanwhile, the variables of concentration time, length of the main waterway, area, slenderness ratio, perimeter and slope have a higher correlation with the amount of sediment production in the basins than other variables. Among these variables, the basin concentration time variable was used in the final step-by-step regression model and was selected as the sediment predictor variable. This variable alone can predict 98% of annual precipitation. In order to ensure the appropriateness of the data, the KMO coefficient was used to analyze the main components. The value of KMO = 0.78, as a result, the data will be suitable for factor analysis. The results showed that the four factors of area, main waterway length, concentration time and elongation factor could explain 88.754% of the variance of all research variables. [ABSTRACT FROM AUTHOR]

Background and Objectives: Cotton yield and most important traits in terms of economic and breeding values are polygenic traits, and direct selection for them has not been very successful. This study was conducted to identify the relationships between yield and its related traits and to determine the most important traits affecting cotton lint-yield. Materials and Methods: an experiment including nine genotypes with two commercial varieties of Fars province (Bakhtegan and Golestan) as controls, in a randomized complete blocks design with four replications, was carried out at Darab Agricultural Research Station during two years of 2017 and 2018. In this study, the traits of plant height, monopodial length, monopodial number, sympodial length, sympodial number, number of boll per plant, boll weight, earliness percentage and lint-yield were investigated. Results: The combined variance analysis results for the studied traits showed that the genotype had a significant effect on all traits except for the monopodial length and the sympodial number at the 1% probability level. The comparison of genotype means showed that the genotypes A-NB414 and A-NBK had the highest lint-yield of 5445 and 5154 kg/ha, respectively. The lint-yield of these two genotypes were significantly different from those of the other genotypes. The genotypes A-NB414 and A-NBK also had higher values for plant height, sympodial number, number of boll per plant, and earliness percentage than the other genotypes. The phenotype correlation analysis showed a significant positive correlation between lint-yield and number of boll per plant (r=0.80**), boll weight (r=0.36**), and plant height (r=0.60**) at the 1% probability level. The stepwise regression analysis results showed that the traits of number of boll per plant, boll weight, plant height, and sympodial length had the most significant effects on cotton lint-yield (R² =0.77). According to the results of the path analysis, the number of boll per plant had the most direct effect on lint-yield (P=0.78). The indirect effect of plant height on lint-yield was exerted through the number of boll per plant. The lint-yield of these two genotypes was significantly different from other genotypes. A-NB414 and A-NBK genotypes were superior to other genotypes in plant height, sympodial number, number of boll per plant, and earliness percentage. The phenotypic correlation showed a high and significant correlation at 1% level of probability respectively between the lint-yield and the number of boll per plant (r=0.80**), boll weight (r=0.36**) and plant height (r=0.60**). The results of step-by-step regression analysis showed that the traits of boll number, boll weight, plant height and sympodial length explain the most lint-yield changes (R2 =77.59). According to the results of the path analysis, the most direct effect on the lint-yield trait was related to the number of boll per plant (P=0.78). The most indirect effect of plant height was exerted on lint-yield through the number of boll per plant. Conclusion: Considering the very high correlation between the lint-yield and the number of boll per plant, it can be concluded that the number of boll per plant is the main factor causing genotype differences in lint-yield. Since boll weight, number of boll per plant and plant height have the largest direct effects on cotton lint-yield, these traits can be used as selection criteria. Additionally, since the number of boll per plant has the most direct and indirect effect on lint-yield, it can be used to increase lintyield in breeding programs. [ABSTRACT FROM AUTHOR]

Introduction Pepper is a rich source of essential vitamins and minerals. Like tomatoes, pepper plays an important role in preventing heart diseases due to its high amount of antioxidants. Fruit yield is a complex trait that is not only controlled by several genes, but also greatly influenced by the environment. On the other hand, fruit yield is affected by a large number of other traits and their interaction. Therefore, it is very important for plant breeders to know the relationships between these traits and their interaction effects. The path coefficient analysis is a method that clarifies the relationships between traits and their direct and indirect effects on fruit yield. In this method, the correlation coefficient between two attributes is divided into components that measure direct and indirect effects. Considering the limited studies regarding the evaluation of relationships between fruit yield and other traits affecting fruit yield in pepper, this research was conducted with the aim of identifying these important relationships and evaluating their direct and indirect effects in Iranian pepper populations. Materials and Methods In order to carry out this research, the seeds of 30 Iranian pepper accessions were collected directly from the farmers. The experiment was conducted in the form of pot cultivation in the research greenhouse of the Faculty of Agriculture of Urmia University in a completely randomized design with five replications during 2015-2016. After the flowering stage, the desired traits were estimated. Variance analysis was estimated, after examining the basic hypotheses of variance analysis by SAS9.4, as well as the genotypic and phenotypic correlation between traits based on the restricted maximum likelihood (REML) procedure in the SAS9.4 software. Step-by-step regression analysis was used to determine the traits with the most variation justified the fruit yield. The Durbin-Watson test was performed to investigate the independence of experimental errors. Analysis of path coefficients was performed based on the results of stepwise regression and genotypic correlation of traits in the R V.4.0.5. Results and Discussion In order to understand the relationships between traits and use them in breeding programs, the phenotypic correlation was estimated. In this study based on the results of phenotypic correlation, leaf width and leaf length (0.651), single fruit weight and fruit circumference (0.784), fruit circumference and fruit diameter (0.625) and pulp weight and fruit diameter (0.610), showed positive and significant correlation. The purpose of estimating genotypic correlation coefficient is to determine relationships in conditions which in environmental factors are not involved. In the investigation of genotypic correlation, a positive, strong and significant relationship between fruit yield and pulp weight (0.907), fruit circumference (0.891), fruit diameter (0.697), single fruit weight (0.646) and around the plant (0.381) were observed. Given that most of these traits are factors contributing to fruit yield, the presence of such positive and significant genotypic correlation coefficients is reasonable. It can be inferred that pepper accessions with higher fruit characteristics, encompassing factors such as plant density and branching, are likely to exhibit higher fruit yields as well. It's important to note that correlation coefficients are mathematical tools used to measure the linear relationship between two variables. Their significance lies in their mathematical interpretation, and as such, they alone do not provide sufficient proof of a cause-and-effect relationship. Utilizing the results of stepwise regression, less impactful traits or those with minimal effects were eliminated from the model. As a result, seven key traits were identified as the most influential factors affecting fruit yield: pulp weight, plant density, fruit diameter, fruit count, plant height, total seed weight, and branch count.The first characteristic was pulp weight, which was included in the model and explained 78.8% of the fruit yield changes between genotypes. The second characteristic (around the plant) along with pulp weight explained 80.9% of the fruit yield variations. Fruit diameter, together with the previous two characteristics, explained 81.5% of fruit yield variations. In total, the traits included in the model for fruit yield justified 84.6% of the total changes in fruit yield in 30 pepper accessions. In order to better understanding and more accurately interpret of the results, as well as to know the direct and indirect effects and the effect of the traits that were entered into the model through stepwise regression, the path coefficient analysis method was used in this research. Fruit diameter (0.709) and pulp weight (0.289) respectively showed the most positive and direct effect on fruit yield. Fruit pulp weight through fruit diameter had the most positive indirect effect (0.595) on fruit yield. Around the plant showed an indirect positive effect on fruit yield through pulp weight (0.157), fruit diameter (0.392) and number of branches (0.080). Conclusion In the present study, the trait of fruit diameter had a positive, strong and significant genotypic correlation (0.697) with fruit yield, and it also showed a positive direct effect (0.709) on fruit yield, these two coefficients can be considered equal, Approximately. Therefore, direct selection based on fruit diameter proves to be a valuable strategy for enhancing fruit yield. The magnitude of residual effects serves as an indicator of the model's accuracy in path analysis. When this value is substantial, it may be advisable to incorporate additional causal variables into the model. In the current study, the residual effects value (0.213) affirms the model's optimal accuracy.This research highlights the effectiveness of employing stepwise multivariate regression and path coefficient analysis to gain a deeper understanding of the fundamental relationships between traits. It underscores that relying solely on correlation relationships is insufficient for comprehensively justifying the associations between these traits.

The effect of heat stress on yield, yield component and some agronomic traits of barley, was evaluated during the growing season of 2022-2023 using a randomized complete block design with three replications under normal and heat stress conditions. Eight barley cultivars including Nik, Mehr, Khatam, Reyhan, Nosrat, Fajr 30, Yoosef and Afzal were grown in Abarkouh, Yazd, central Iran. The results of combined analysis of variance revealed that cultivar effect was significant in all traits except 1000 grain weight and peduncle length. Heat stress × cultivar interaction was significant for spikes/m2, grains/spike, and grain yield. Heat stress led to a significant decrease in days from sowing to physiological maturity, plant height, peduncle and spike length, spikes/m2, grains/spike, and grain yield and a significant increase in days from sowing to tillering. Grain yield under both conditions had significant negative correlation with days from sowing to tillering. Grain yield had significant positive correlation with spikes/m2 under normal condition and with spikes/m2, and grains/spike under heat stress condition. Stepwise regression results showed that grains/spike and plant height could be used as criteria for increaseing grain yield under heat stress condition. Mean comparison of data for studied cultivars showed that Reyhan and Nosrat genotypes could be suggested for cultivation under both conditions.

The effect of heat stress on yield, yield component and some agronomic traits of barley, was evaluated during the growing season of 2022-2023 using a randomized complete block design with three replications under normal and heat stress conditions. Eight barley cultivars including Nik, Mehr, Khatam, Reyhan, Nosrat, Fajr 30, Yoosef and Afzal were grown in Abarkouh, Yazd, central Iran. The results of combined analysis of variance revealed that cultivar effect was significant in all traits except 1000 grain weight and peduncle length. Heat stress × cultivar interaction was significant for spikes/m², grains/spike, and grain yield. Heat stress led to a significant decrease in days from sowing to physiological maturity, plant height, peduncle and spike length, spikes/m2, grains/spike, and grain yield and a significant increase in days from sowing to tillering. Grain yield under both conditions had significant negative correlation with days from sowing to tillering. Grain yield had significant positive correlation with spikes/m2 under normal condition and with spikes/m², and grains/spike under heat stress condition. Stepwise regression results showed that grains/spike and plant height could be used as criteria for increaseing grain yield under heat stress condition. Mean comparison of data for studied cultivars showed that Reyhan and Nosrat genotypes could be suggested for cultivation under both conditions. [ABSTRACT FROM AUTHOR]

AbstractThe purpose of the current study is to analyze the frequency of peak flood discharge with a 100-year return period in 206 Iran watersheds and to quantify it based on the most important factors. In this regard, flood frequency analysis was performed based on annual maximum discharge data and fitting of conventional continuous distributions in hydrology and fitting statistical tests. Then, for modeling, 8 parameters affecting the flood peak discharge including heavy daily rainfall, average vegetation, area, perimeter, average slope, average elevation, length of the main river, and the slope of the main river at the catchment area leading to the extraction of selected hydrometric stations. Also, the stepwise regression analysis technique was used to determine the factors affecting the production of flood peak discharge in the selected stations. The results of the study showed that the southwestern, southern, and southeastern basins of Iran with peak discharges of more than 4000 m3/s had the highest 100-year peak discharges among the study basins. The results of the stepwise regression model indicated that five parameters of area, heavy rainfall, elevation, vegetation, and slope of the basin with an adjusted coefficient of determination of 0.72, standard error of estimation of 132.7, Akaike's information criterion of 1.62, and variance inflation factor of 0.62 had the best performance in estimating the flood peak discharge. The results of this study, considering its large spatial scale, which includes the whole of Iran, can be used as a practical guide by the hydrologists and decision-makers in estimating the 100-year flood peak discharge in ungauged watersheds based on the most important factors affecting its generations. IntroductionFlood is one of the most important natural hazards that has attracted a lot of attention from managers and planners due to the heavy damage it has caused to human societies (Jahangir et al., 2019). In fact, floods, as a type of natural disaster, have a significant negative impact on regional development, and its catastrophes are characterized by sudden water flow, high intensity, uncontrollable factors, and serious damages (Miceli et al., 2008). On the other hand, among various types of natural disasters such as earthquakes, landslides, soil erosion, and tsunamis, floods are considered to be the most common and destructive phenomena of the earth that affect the lives of many people every year (Doocy et al., 2013; Salvati et al., 2018; Yari et al., 2019). High socio-economic losses, human casualties, widespread destruction, and threatening living conditions are some of the damages that floods can cause (Turgut & Tevfik, 2012). It can be stated that half of the deaths occur due to floods (FitzGerald et al., 2010; Lee & Vink, 2015). In recent years, Iran has experienced very destructive floods due to climate change and poor watershed management (deforestation, overgrazing, and lack of flood control measures). For example, the recent floods (2019) in Iran have affected 25 provinces, killed 77 people, and caused about $ 2.2 billion in damage to these 25 provinces (Khosravi et al., 2020). MethodologyIn the first step, the Iran hydrometric stations that had discharge data with maximum long-term annual peak records (at least 30 years) were collected from the Iran Water Resources Management Company. In the next step, flood frequency analysis was performed based on the fitting of conventional continuous distributions in hydrology and fitting statistical tests. After performing flood frequency analysis and estimating peak discharge for 100 year return period, the watersheds boundary of hydrometric stations was determined. In this regard, using a digital elevation model with 12.5 m resolution and ARC GIS, Global Mapper, and Surfer software, the boundaries of the studied watersheds were extracted. Then, using the watersheds boundary and digital elevation model, the geomorphic parameters of the watershed such as perimeter, area, average slope, average elevation, length of the main river, and the slope of the main river were calculated. In the next step, long-term daily precipitation data of synoptic stations were collected from Iran Meteorological Organization. Then, 95% of the non-zero daily precipitation series was calculated for heavy precipitation (Gu et al., 2017). Using the IDW method, the long-term amount of heavy rainfall for each watershed was determined in GIS software. The NDVI index was used to determine the mean annual vegetation. In this regard, the vegetation time series for each watershed was extracted using Landsat images from 2000 to 2019 with a resolution of 30 m on the Google Earth Engine platform. After calculating the 100-year return period and possible parameters influencing the flood in the study watersheds, using Pearson bivariate analysis and stepwise regression model, the most suitable models for estimating flood peak discharge were determined. DiscussionThe results of the study show that the southwestern, southern, and southeastern watersheds of Iran with peak discharges of more than 4000 cubic meters per second have the highest peak discharges of 100 years among the study watersheds. Meanwhile, the Minab watershed, which ends in the Persian Gulf, has a maximum peak flow of 100 years with a peak flow of 12,614 cubic meters per second. On the other hand, the northwestern and northern watersheds of Iran with a peak discharge of less than 300 cubic meters per second have the lowest peak discharge, with a minimum discharge of 20.7 cubic meters per second related to the Solan watershed in Hamadan province. The findings of the stepwise regression model indicated that the five parameters of the watershed, including area, heavy rainfall, mean elevation, vegetation, and mean slope with R2 = 0.72 and significance level of 0.01, are the most influential factors in the estimation of flood peak discharge. In addition, the results showed that the three factors of watershed area, heavy rainfall, and mean slope have a direct relationship with peak discharge but mean elevation and vegetation have an inverse relationship. ConclusionThis study quantified the relative contribution of driving factors influencing the flood peak discharge over 100 years across Iran. Considering its large spatial scale, which includes the whole of Iran, it can be used as a practical guide by the hydrologists and decision-makers in estimating the 100-year flood peak discharge in ungauged watersheds based on the most important factors affecting its generations. Keywords: Flood Peak Discharge, Modeling, Iran’s Watersheds, Stepwise Regression, Geomorphic Factors. References- Adhikari, P., Hong, Y., Douglas, K. R., Kirschbaum, D. B., Gourley, J., Adler, R., & Brakenridge, G. R. (2010). A digitized global flood inventory (1998–2008): Compilation and preliminary results. Journal of Natural Hazards, 55(2), 405–422.- Ahern, M., Kovats, R. S., Wilkinson, P., Few, R., & Matthies, F. (2005). Global health impacts of floods: Epidemiologic evidence. Journal of Epidemiologic Reviews, 27(1), 36–46.- Bennett, B., Leonard, M., Deng, Y., & Westra, S. (2018). An empirical investigation into the effect of antecedent precipitation on flood volume. Journal of Hydrology, 567, 435–445.- Chang, H. S., & Chen, T. L. (2016). Spatial heterogeneity of local flood vulnerability indicators within flood-prone areas in Taiwan. Journal of Environmental Earth Sciences, 75(23), 1-14.- Chau, K. W. (2017). Use of meta-heuristic techniques in rainfall-runoff modelling. Basel, Switzerland: Multidisciplinary Digital Publishing Institute.- Chuntian, C., & Chau, K. W. (2002). Three-person multi-objective conflict decision in reservoir flood control. European Journal of Operational Research, 142(3), 625–631.- Croke, J., Thompson, C., & Fryirs, K. (2017). Prioritising the placement of riparian vegetation to reduce flood risk and end-of-catchment sediment yields: Important considerations in hydrologically-variable regions. Journal of Environmental Management, 190, 9–19.- Doocy, S., Daniels, A., Packer, C., Dick, A., & Kirsch, T. D. (2013). The human impact of earthquakes: A historical review of events 1980-2009 and systematic literature review. Journal of Plos Currents, 5.- El-Hames, A. S. (2012). An empirical method for peak discharge prediction in ungauged arid and semi-arid region catchments based on morphological parameters and SCS curve number. Journal of Hydrology, 456, 94-100.- Ezemonye, M. N., & Emeribe, C. N. (2011). Flood characteristics and management adaptations in parts of the Imo river system. Ethiopian Journal of Environmental Studies and Management, 4(3), 56–64.- Falah, F., Rahmati, O., Rostami, M., Ahmadisharaf, E., Daliakopoulos, I. N., & Pourghasemi, H. R. (2019). Artificial neural networks for flood susceptibility mapping in data-scarce urban areas. In Spatial modeling in GIS and R for Earth and Environmental Sciences (pp. 323-336). Elsevier.- Feng, L. H., & Lu, J. (2010). The practical research on flood forecasting based on artificial neural networks. Journal of Expert Systems with Applications, 37(4), 2974–2977.- FitzGerald, G., Du, W., Jamal, A., Clark, M., & Hou, X. (2010). Flood fatalities in contemporary Australia (1997–2008). Journal of Emergency Medicine Australasia, 22(2), 180–186.- Ghavidel, Y., & Hombari, F. J. (2020). Synoptic analysis of unexampled super-heavy rainfall on April 1, 2019, in west of Iran. Journal of Natural Hazards, 104(2), 1567-1580.- Gu, X., Zhang, Q., Singh, V. P., & Shi, P. (2017). Changes in magnitude and frequency of heavy precipitation across China and its potential links to summer temperature. Journal of Hydrology, 547, 718–731.- Haghizadeh, A., Siahkamari, S., Haghiabi, A. H., & Rahmati, O. (2017). Forecasting flood-prone areas using Shannon’s entropy model. Journal of Earth System Science, 126(3), 1-11.- Haynes, K., Coates, L., van den Honert, R., Gissing, A., Bird, D., de Oliveira, F. D., … & Radford, D. (2017). Exploring the circumstances surrounding flood fatalities in Australia, 1900–2015 and the implications for policy and practice. Journal of Environmental Science & Policy, 76, 165–176.- Herget, J., Roggenkamp, T., & Krell, M. (2014). Estimation of peak discharges of historical floods. Journal of Hydrology and Earth System Sciences, 18(10), 4029.- Jahangir, M. H., Reineh, S. M. M., & Abolghasemi, M. (2019). Spatial predication of flood zonation mapping in Kan River Watershed, Iran, using artificial neural network algorithm. Journal of Weather and Climate Extremes, 25, 100215.- Khosravi, K., Panahi, M., Golkarian, A., Keesstra, S. D., Saco, P. M., Bui, D. T., & Lee, S. (2020). Convolutional neural network approach for spatial prediction of flood hazard at national scale of Iran. Journal of Hydrology, 591, 125552.- Khosravi, K., Pourghasemi, H. R., Chapi, K., & Bahri, M. (2016). Flash flood susceptibility analysis and its mapping using different bivariate models in Iran: A comparison between Shannon’s entropy, statistical index, and weighting factor models. Journal of Environmental Monitoring and Assessment, 188(12), 1-21.- Kirch, W., Menne, B., & Bertollini, R. (Eds.). (2005). Extreme weather events and public health responses. Berlin, Heidelberg: Springer Berlin Heidelberg.- Lashkari, H., Mohammadi, Z., & Jafari, M., 2020. Investigation on dynamical structure and moisture sources of heavy precipitation in south and south-west of Iran. Arabian Journal of Geosciences, 13(21), 1-15.- Lee, S., & Vink, K. (2015). Assessing the vulnerability of different age groups regarding flood fatalities: Case study in the Philippines. Journal of Water Policy, 17(6), 1045–1061.- Liu, D., Fan, Z., Fu, Q., Li, M., Faiz, M. A., Ali, S., … & Khan, M. I. (2020). Random forest regression evaluation model of regional flood disaster resilience based on the whale optimization algorithm. Journal of Cleaner Production, 250, 119468.- Liu, Y., Yuan, X., Guo, L., Huang, Y., & Zhang, X. (2017). Driving force analysis of the temporal and spatial distribution of flash floods in Sichuan Province. Journal of Sustainability, 9(9), 1527.- Machado, R. A. S., Oliveira, A. G., & Lois-González, R. C. (2019). Urban ecological infrastructure: The importance of vegetation cover in the control of floods and landslides in Salvador/Bahia, Brazil. Journal of Land Use Policy, 89, 104180.- Mallakpour, I., Villarini, G., Jones, M. P., & Smith, J. A. (2017). On the use of Cox regression to examine the temporal clustering of flooding and heavy precipitation across the central United States. Journal of Global and Planetary Change, 155, 98-108.- Miceli, R., Sotgiu, I., & Settanni, M. (2008). Disaster preparedness and perception of flood risk: A study in an alpine valley in Italy. Journal of Environmental Psychology, 28(2), 164–173.- Norouzi, G., & Taslimi, M. (2012). The impact of flood damages on production of Iran’s agricultural sector. Middle East Journal of Scientific Research, 12, 921-926.- Ogato, G. S., Bantider, A., Abebe, K., & Geneletti, D. (2020). Geographic information system (GIS)-Based multicriteria analysis of flooding hazard and risk in Ambo Town and its watershed, west Shoa zone, Oromia regional state, Ethiopia. Journal of Hydrology: Regional Studies, 27, 100659.- Sadeghi-Pouya, A., Nouri, J., Mansouri, N., & Kia-Lashaki, A. (2017). An indexing approach to assess flood vulnerability in the western coastal cities of Mazandaran, Iran. International Journal of Disaster Risk Reduction, 22, 304-316.- Saksena, S., & Merwade, V. (2015). Incorporating the effect of DEM resolution and accuracy for improved flood inundation mapping. Journal of Hydrology, 530, 180-194.- Salvati, P., Petrucci, O., Rossi, M., Bianchi, C., Pasqua, A. A., & Guzzetti, F. (2018). Gender, age and circumstances analysis of flood and landslide fatalities in Italy. Journal of Science of the Total Environment, 610, 867–879.- Seckin, N., & Guven, A. (2012). Estimation of peak flood discharges at ungauged sites across Turkey. Journal of Water Resources Management, 26(9), 2569-2581.- Shabanikiya, H., Seyedin, H., Haghani, H., & Ebrahimian, A. (2014). Behavior of crossing flood on foot, associated risk factors and estimating a predictive model. Journal of Natural Hazards, 73(2), 1119–1126.- Shahabi, H., Shirzadi, A., Ronoud, S., Asadi, S., Pham, B. T., Mansouripour, F., … & Bui, D. T. (2021). Flash flood susceptibility mapping using a novel deep learning model based on deep belief network, back propagation and genetic algorithm. Journal of Geoscience Frontiers, 12(3), 101100.- Smith, K. (2013). Environmental hazards: Assessing risk and reducing disaster. Routledge.- Tang, J., Li, Y., Cui, S., Xu, L., Hu, Y., Ding, S., & Nitivattananon, V. (2021). Analyzing the spatiotemporal dynamics of flood risk and its driving factors in a coastal watershed of southeastern China. Journal of Ecological Indicators, 121, 107134.- Turgut, A., & Tevfik, T. (2012). Floods and drowning incidents by floods. Journal of World Applied Sciences, 16(8), 1158–1162.- Wang, C., Du, S., Wen, J., Zhang, M., Gu, H., Shi, Y., & Xu, H. (2017). Analyzing explanatory factors of urban pluvial floods in Shanghai using geographically weighted regression. Journal of Stochastic Environmental Research Risk Assessment, 31(7), 1777-1790.- Yari, A., Ardalan, A., Ostadtaghizadeh, A., Zarezadeh, Y., Boubakran, M. S., Bidarpoor, F., & Rahimiforoushani, A. (2019). Underlying factors affecting death due to flood in Iran: A qualitative content analysis. International Journal of Disaster Risk Reduction, 40, 101258.- Zorn, C. R., & Shamseldin, A. Y. (2015). Peak flood estimation using gene expression programming. Journal of Hydrology, 531, 1122-1128.

IntroductionFenugreek (Trigonella foenum-graecum) is an annual plant belong to Fabaceae and is one of the traditional medicinal plants worldwide. It can provide seed and protein suitable for human's nutrition as well as animals. Water scarcity is a key threat in twenty-first century. On average, 40% of the world land surface are drylands, while this surface area is 90% in Iran. Supplying water requirement of Fenugreek through irrigation is an important factor affecting its growth and yield.Material and MethodsThe experiment was conducted as split plots based on randomized complete block design with three replications at the Research Farm, Faculty of Agriculture of shahed university, Iran, in 2014 and 2016. The main-plot was three levels of drought stress, included severe drought stress (20% field capacity), moderate drought stress (40% field capacity), mild drought stress (60% field capacity) and non-drought stress (80% field capacity) as control. Sub plots were nine Fenugreek ecotypes including Neyshabur, Shirvan, Mashhad, Tabriz, Roudsar, Isfahan, Hamadan, Ardestan and Shiraz. At maturity, and the plants were harvested from the soil surface and the plant height and number of lateral branches, number of pod per plant, number of seed per pod, 1000 seed weight, seed yield and aboveground biological yield were measured in the lab. Statistical analysis carried out using SPSS version 16 software. Significant difference was set at p ≤ 0.05 by using Duncan’s multiple range test.Results and DiscussionResults of stepwise regression showed that the traits including biomass, harvest index, branch length and number of pods per plant explained 96.7% of grain yield variation, respectively. Factor analysis for morphologic, yield and component yield traits showed the first three independent factors explained 93.48% of total variance in all genotypes. Days to maturity with 36.47% of total variance had the highest amount in the first factor, while, number of seeds per plant and seed yield with 29.74% and 27.07% of total variance were ranked as second and third factors, respectively. Cluster analysis by Ward’s minimum variance, clustered ecotypes into three groups including 1- Isfahan, Ardestan, Hamedan and Shiraz 2- Mashhad and Tabriz 3- Shirvan, Rudsar and Neyshabur. The results showed that, the plant height, Internode length, number of pod and seed per plant, 1000 seed weight, biological and seed yield and harvest index significantly affected by drought stress and ecotypes. The highest plant height, number of pods, 1000 seed weight, biomass, seed yield and harvest index was recorded in Shirvan ecotype while, the longest day to maturity and height of first pod were observed in Neyshabur ecotype at 80% FC. The highest plant height, the first formed pod, 1000 seed weight, seed yield and harvest index in Shirvan ecotype were observed in the 40% FC.ConclusionDrought stress reduced all studied traits in all Fenugreek ecotypes in this experiment. For seed yield, the performance of shirvan ecotype was the best compare to other ectypes in control and mild and moderate stress condition. The highest distance of the first pod from the soil surface in the control condition was observed in the Neyshabur ecotype but in the moderate stress condition in Shirvan ecotype, this trait is important for the mechanized cultivation. Based on the results, there is a reliable variation amongst different Iranian Fenugreek ecotypes and they could use for breeding programs against drought stress. It also seems that Shirvan ecotype of Fenugreek can be considered for stable seed and biomass production under moderate drought stress and normal conditions.

Due to the increasing need of the country to imported edible oil and rapeseed importance among oilseeds, efforts to increase its grain yield and oil content are of high importance. Therefore, recognizing the traits that increase grain yield of rapeseed has an important role in the success of breeding programs. Thus, sixteen rapeseed genotypes were evaluated in a randomized complete block design with three replications in three regions with different climatic conditions in Iran, including Karaj, Isfahan, and Hamadan in 2016-2017. Traits such as number of pods per plant, number of seeds per pod, grain yield, 1000-grain weight, plant height, height of the first branch, stem diameter, oil percent, number of days to flowering, number of days to the end of flowering, duration of flowering, and number of days to maturity were measured. Stepwise regression analysis showed that number of grain/pod, number of days to maturity and number of pods/plant (R2 = 97.7), number of pods/plant and number of days to maturity (R2 =78.4) and number of days to maturity and number of grains/pod (R2 = 45.5) accounted for total variations of grain yield in Karaj, Isfahan and Hamadan, respectively. The results showed that the number of days to maturity, number of pods/plant, number of grain/pods, stem diameter and plant height had the greatest positive effect on grain yield and oil content. Therefore, these traits can be used as suitable selection tools for increasing grain and oil yield in winter rapeseed breeding programs

To evaluate the genetic diversity and relationships among traits of herbaceous milkvetch, ten genotypes belonging to five species, including Astragalus vegetus. A. brevidens, A. brachyodontus, A. effusus, and A. cyclophyllus in Sanandaj in a randomized complete block design with three replications were studied. Seed sowing was done in November 2018, and morphological traits of the plant in spring 2020 were measured. Analysis of variance indicated that significant (p≤0.01 and 0.05) difference for milkvetch populations (G) for all studied traits. In 2020 (two years old plants), the mean of plant establishment was about 26%, the number of primary branches was 3.2, the plant height, the tallest stem length, and crown diameter was 16.9, 19.2, and 15.4 cm, respectively, and the length and width of the root were 17.4 and 6.2 cm, respectively, the average of fresh weights of the whole plant, aerial and root parts was 2.3, 1.9 and 0.4 g and the average weight of the plant, aerial and root parts were 0.9, 0.7 and 0.2 g respectively, average dry to fresh weight ratio was 0.38. The average number of leaflets per leaf was 7.7, so the mean length and width of leaf and leaflets were 7.5, 3.7, 2.3, and 0.5 cm, respectively. The accession of A. effusus Darreh Shohada (West Azerbaijan) and three accessions of A. vegetus (Zereshk of Qazvin, Saral of Kurdistan, and Qarehbagh of West Azerbaijan) were superior ones in terms of forage production and other studied traits. The weight of the plant was positively correlated with plant vigor, length, and width of the leaf (p≤0.05) and with plant height, crown diameter, number of primary branches, the length and width of the root, aerial and root weight at (p≤0.01). The results of stepwise regression of forage yield on other traits showed that plant weight, establishment percentage, plant height, and crown diameter at (p≤0.01) and the length of leaf and root at (p≤0.05) with (R2adj = 91.1%) were forage yield components. Therefore, to achieve higher forage, genotypes with larger aerial parts and deeper roots should be selected. [ABSTRACT FROM AUTHOR]

In this study, spatial-temporal variation of dust deposition rate in the western and eastern half of Tehran and its climatic parameters affecting were studied. At 34 points in the city, dust samples were collected by glass traps from the roof, for twelve months, and the climatic data were obtained and analyzed from relevant organizations. The highest deposition rate is in the western half of the city and its total amount has varied from 54.52 to 121.21 g/m2/y. In both halves of the city, summer has the highest dust deposition rate and its central areas have the highest amount. There were significant positive correlations between dust deposition rate with temperature and medium wind speed, and there were significant negative correlations between dust deposition rate with rainfall and relative humidity in all months, which justifies the high dust deposition rate in the dry seasons of the year. The results of stepwise regression showed that rainfall was the most important factor affecting the dust deposition rate in both halves of the city. The city of Tehran has a special geographical location the presence of mountains like a barrier has prevented dust from leaving the city and the air inlet corridor of Tehran has faced problems due to the expansion of building construction and high-rise building. Other factors affecting the rate of dust deposition in this city, in addition to the distance from the main source of dust production, atmospheric parameters can be mentioned the existence of barren lands around the city, vegetation cover, construction operations, and traffic.

Background and objectives: A proper planting date in canola allows the crop to grow sufficiently and minimizes the damaging effects of stress. On the other hand, early autumn rains and the problem of timely farm preparation and unavailability of farm fields due to summer crops such as peanuts in the Moghan region cause delays in planting dates for autumn crops such as canola. Problems such as supplying primary soil water for crop establishment of canola fields, pest damage such as flea beetles in delayed cultivation, the possibility of damage from cold and frost stress, as well as the decline in yield due to canola exposure to drought and heat stress due to delayed planting are the main problems of canola cultivation in the Moghan region. Because of this, canola transplanting can solve the problems and be a good choice in these kinds of situations. Materials and methods: In order to agronomic evaluation of direct cultivation and transplantation of spring canola in different plant densities under delayed conditions in the Moghan region, an experiment was conducted as a randomized complete block design with three replications in two cropping years, 2019-2020 and 2020-2021. Experimental treatments included direct sowing of seeds as a control at a rate of 6 kg/ha; transplanting with densities of 20, 30, and 40 plants per square meter, each density with both bare-root transplant and potted-root transplant; and also with one seedling or two seedlings in the planting hole. During the experiment, traits including flowering initiation, flowering completion, flowering period, growth period, plant height, first pod height, stem diameter, branch number, pod length, pod thickness, pod number, seed number per pod, 1000-seed weight, and seed yield were recorded. Correlations among traits and path analysis were performed to investigate seed yield's direct and indirect effects. Results: The results showed that transplanting on average caused a significant decrease in phenological traits such as flowering initiation (145.5 GDD), flowering completion (207.8 GDD), growth period (158.9 GDD), and increased flowering period (156.6 GDD) during the experimental years. Also, transplanting caused a significant increase in stem diameter (2.8 mm), branch number (2.3), pod diameter (0.6 mm), number of pods per plant (158.2), number of seeds per pod (3.3), 1000-seed weight (0.69 g) and seed yield (1894.4 kg/ha). In control treatment as delayed direct sowing, seed yield in total experimental years showed a yield decline of 62.2% (1150.7 kg/ha) compared to transplanting cultivation treatments (3045.1 kg/ha). Comparing the bare-root transplant treatments, it was found that 40 plants per square meter had a higher number of pods per plant, 1000-seed weight, and seed yield than the 30 and 20 treatments and had a significant difference with them. Phenotypic correlation among agronomic traits showed seed yield had a negative and significant correlation with phenological traits: flowering initiation (-0.90**), flowering completion (-0.90**), and growth period (-0.77**) with a positive and non-significant effect on the flowering period (0.52). The results of stepwise regression analysis showed that the number of pods per plant (0.241*) and pod thickness (0.229*) had the most significant direct and positive effects on seed yield, respectively, while flowering completion (-0.559**) had the most negative and significant direct effect on seed yield. Conclusion: Under delayed conditions, bare-root transplanting of canola with 40 plants per square meter density and one seedling in the planting hole was superior in terms of seed yield and phenological traits compared to potted-root transplanting and direct cultivation and is recommended in Moghan region. [ABSTRACT FROM AUTHOR]

Due to the increasing need of the country to imported edible oil and rapeseed importance among oilseeds, efforts to increase its grain yield and oil content are of high importance. Therefore, recognizing the traits that increase grain yield of rapeseed has an important role in the success of breeding programs. Thus, sixteen rapeseed genotypes were evaluated in a randomized complete block design with three replications in three regions with different climatic conditions in Iran, including Karaj, Isfahan, and Hamadan in 2016-2017. Traits such as number of pods per plant, number of seeds per pod, grain yield, 1000-grain weight, plant height, height of the first branch, stem diameter, oil percent, number of days to flowering, number of days to the end of flowering, duration of flowering, and number of days to maturity were measured. Stepwise regression analysis showed that number of grain/pod, number of days to maturity and number of pods/plant (R² = 97.7), number of pods/plant and number of days to maturity (R² =78.4) and number of days to maturity and number of grains/pod (R² = 45.5) accounted for total variations of grain yield in Karaj, Isfahan and Hamadan, respectively. The results showed that the number of days to maturity, number of pods/plant, number of grain/pods, stem diameter and plant height had the greatest positive effect on grain yield and oil content. Therefore, these traits can be used as suitable selection tools for increasing grain and oil yield in winter rapeseed breeding programs. [ABSTRACT FROM AUTHOR]

Droughts are intrinsically regional. The critical conditions in the dry periods occur when there is a severe shortage of water resources for a long period on a wide area. Therefore, an investigation of the regional and not of a local drought offers better understanding of this phenomenon. This study aims at a regional analysis of the hydrological drought in East Azarbaijan Province for a period of 45 years (1972– 2017) using the data collected at 25 hydrometric stations with proper spatial distribution across the province. Homogeneous hydrological areas was identified based on hierarchical analysis method in the SPSS software using the following independent variables: Area, Perimeter, Length of the main basin, Main channel gradient, Drainage density, Basin shape factor, Total hydrographic network, Weighted average slope of the basin, Maximum, Minimum and Median height of the basin, and its length. Frequency analysis and probability distribution of the dependent variables (duration and intensity of hydrological drought spells) was performed on the basis of the two year return period for each hydrometric station. The factor analysis was performed using the PCA method in the SPSS software. The suitability of the data for the factor analysis was evaluated using the KMO coefficient. The value of this coefficient was estimated as 0.546, which indicates that the data were suitable for factor analysis. The result of factor analysis showed that the contribution of perimeter, height and shape of the basin were 40.13, 26.42 and 13.12% (Sum 79.68 % ) respectively in explaining the variance of the variables (i.e. the most important factors in zoning). Results of regional analysis using multivariable regression (stepwise method) indicated that perimeter, avrage height and the basin shape coefficient have a decisive role in estimating the drought severity and its duration with two-year return period in East Azarbijan. In the scarcity of hydrometric stations in most of the watersheds of the East Azarbaijan province, the regional equation presented in this study can be used to estimate hydrological drought characteristics of watersheds without observed surface runoff data.

In this study, spatial-temporal variation of dust deposition rate in the western and eastern half of Tehran and its climatic parameters affecting were studied. At 34 points in the city, dust samples were collected by glass traps from the roof, for twelve months, and the climatic data were obtained and analyzed from relevant organizations. The highest deposition rate is in the western half of the city and its total amount has varied from 54.52 to 121.21 g/m²/y. In both halves of the city, summer has the highest dust deposition rate and its central areas have the highest amount. There were significant positive correlations between dust deposition rate with temperature and medium wind speed, and there were significant negative correlations between dust deposition rate with rainfall and relative humidity in all months, which justifies the high dust deposition rate in the dry seasons of the year. The results of stepwise regression showed that rainfall was the most important factor affecting the dust deposition rate in both halves of the city. The city of Tehran has a special geographical location the presence of mountains like a barrier has prevented dust from leaving the city and the air inlet corridor of Tehran has faced problems due to the expansion of building construction and high-rise building. Other factors affecting the rate of dust deposition in this city, in addition to the distance from the main source of dust production, atmospheric parameters can be mentioned the existence of barren lands around the city, vegetation cover, construction operations, and traffic. [ABSTRACT FROM AUTHOR]

Wild pears are an important rootstock for different pear cultivars and considering it is nearly tolerant to drought stress it is necessary to use different treatments to increase its tolerance to drought stress. Electrolytes leakage is an important and effective factor in response to drought stress and related traits. For this purpose, a factorial experiment was designed in a randomized complete blocks design with three replications to identify the traits affecting electrolytes leakage. These traits were studied in 12 treatments including different levels of drought stress and different concentrations of brassinosteroids on wild pears in spring and summer of 2017 in greenhouse conditions. The result showed a positive significant correlation between proline content (0.83**), malondialdehyde (0.98**), hydrogen peroxide and electrolyte leakage. The correlation for dry weight of root, leaf and stem, height growth, chlorophyll a, b and carotenoid was significantly negative. Stepwise regression analysis indicated that chlorophyll a, leaf dry weight, height growth and hydrogen peroxide were the most important effective traits on electrolytes leakage and showed 99% of total variance. Based on the path analysis results, the traits of electrolytes leakage and height growth and chlorophyll a showed the maximum positive direct and significant at p

To evaluate the genetic variation of Rosa damascena as an important aromatic and medicinal species, 38 genotypes of this species were studied for the diversity of phenological and morphological traits (flowering period, plant height, canopy diameter, number of leaves at the plant, total green area of the plant, number of flowers per plant, fresh weight and percentage of dry matter content of flowers and flower yield per plant) in a randomized complete block design with three replications in Zalleh Research Station of Sanandaj, Iran during 2004-2008. The results showed significant differences (p≤ 0.01) among the genotypes, in terms of the studied traits. The average total yield of fresh flowers was 2427.4 g/plant. The genotypes belonging to temperate and cool areas had lower flower yields than those originated from hot and dry areas. Flower yield showed a significant and positive correlation with the crown height and diameter, the number of leaves, total green surface, and the number of flowers per plant (p ≤ 0.01). The results of stepwise regression showed that the flower weight and number positively, while the total green surface and flowering period negatively correlated with flower yield. The results of cluster analysis (CA) grouping were relatively consistent with segregation based on the flower yield and characteristics of genotypes origin areas. The results of principal component analysis (PCA) showed high consistency with the CA results, but the genotypic separation in PCA method was clearer. The overall results of this study along with CA and PCA analyzes showed considerable rich genetic variation among the genotypes in terms of phenological and morphological traits and the possibility of using this diversity in Iranian Damask rose breeding such as improving flower yield through direct and indirect selections (through flower yield components) or hybridization of genotypes with a greater genetic distance for the use of higher heterosis. [ABSTRACT FROM AUTHOR]

In order to investigate the relationship between quantitative traits and ISSR markers, an experiment was carried out under farm and laboratory conditions at the Zanjan University. In this experiment, 20 primers of ISSR marker were used, and the agronomic traits (including flower number, fresh weight of Stigma, fresh weight of flower, dry weight of Stigma, dry weight of flower, stigma length, saffron yield, corm number, fresh and dry weight of corm, number of leaves, leaf length, leaf width, leaf area, dry leaf weight, biomass, harvest index), physiological traits (transpiration rate, stomatal conductance, photosynthesis) and secondary metabolites (Picocrocin, Safranal, and Crocin) were measured during the growing season. Three primers of the total did not amplify. 17 ISSR primers amplified 133 loci among 20 saffron ecotypes, with an average of 7.82 loci per primer. The highest number of alleles were for the I-8 primer (15 alleles). However, the highest amount of heterozygosity and polymorphism information content was found at the I-7 locus, which was 0.93. The results of stepwise regression analysis showed that the primers studied (i.e., nine primers) had a significant relationship with most traits except the fresh weight of flower, saffranal, crocin, corm number, and transpiration rate. The highest coefficient of determination was related to yield traits (79%), dry leaf weight (76%), flower number (73%), and leaf area (70%), respectively. I-6 locus was associated with nine quantitative traits, which had the highest relationship among studied primers with quantitative traits. This primer was associated with the fresh weight of stigma, dry weight of stigma, fresh and dry weight of corm, leaf number, leaf area, dry leaf weight, stomatal conductance, and photosynthesis. This primer (I-6), showed 11 alleles in the studied population, which can be considered as important primers in relation to quantitative traits. U808 and U834 primers were associated with 5 and 4 traits, respectively, which had the highest association with quantitative traits after the I-6 primer. These primers were associated with the number of flowers, harvest index, and yield. Considering the observed relationship, it is possible to use these markers loci to select ecotypes based on the related traits in saffron populations. [ABSTRACT FROM AUTHOR]

This research was carried out to investigate the relationship between agronomic traits and yield using 132 spring wheat genotypes in alpha-lattice design with two replications at the Agricultural Research Station of Gonbad-e-Kavos. Variance analysis showed that genotypes were significantly different for all traits. The grain yield had very high correlation with the biomass, grain filling duration, seed filling rate, 1000- seed weight, spike weight, Grain weight per spike, days to heading and days to maturity at 1% of probability level. Grain yield was considered as a dependent trait. Biomass, 1000-grain weight and spike length, number and weight were entered into the regression model, respectively. The results showed that in breeding programs with the aim of increasing grain yield, selection should be based on biomass, 1000- grain weight, number and weight of spikes and days to heading. The cluster analysis was performed using the traits introduced into the regression model and traits with high correlation with the performance. Results of cluster analysis showed that genotypes 10, 12, 16, 20, 22, 25, 31, 38, 53, 54, 67, 70, 72, 87, 96, 97, 98, 112 and 123 were in group 4. Genotypes in group 4 were superior to other groups in terms of grain yield, 1000-grain weight, spike weight, grain weight per spike, days to heading and seed filling rate. It is suggested that the genotypes in group 4 should be tested in several years and locations and the best genotype(s) should be introduced. [ABSTRACT FROM AUTHOR]

Introduction Drought, environmental stress is the most common, that about 25 percent of the acreage limit, the occurrence of stress significantly reduced biological yield, grain yield, harvest index and water use efficiency is sometimes. Although the Barley is more tolerant to drought than other cereals, but this plant during its growth and development, in both stem elongation and grain filling sensitive to water deficit, and drought in the steps leading to the reduction of its performance. Flowering stage, the most sensitive growth stage of barley to drought that Water deficit at this stage caused reduces the fertile florets and thus reduce the number of grains per spike. Drought stress from pollination to maturity stage by intensifying the aging of leaves, reduced growth and reduced grain filling rate is decreased average grain weight and grain yield. This research in order to study the yield of barley genotypes in normal irrigation and drought stress conditions as well as analysis of the relationships between traits and grain yield was conducted. Materials and methods The experimental was conducted under normal irrigation and drought stress conditions during 2013-2014 in a RCB design with three replications in college of agricultural, Shiraz University. The plant material used including eight foreign genotype and two Iranian cultivars (cultivar tolerant of Joseph and Reyhan as susceptible), respectively. All the planting, watering and harvesting, but to be quite similar for both experiments were conducted. In normal condition, plants until the end of the growth phase to field capacity (FC) were irrigated, while in drought stress condition, plants were irrigated to field capacity and then drought stress during flowering size for irrigation was applied. To determine the amount of water required in each irrigation of moisture content in soil was used. At the end of the growth phase and after physiological maturity, plant height, the length of the spike, the number of grains per spike, number of grains per spike, grain weight, grain yield, biological yield and harvest index were measured .Statistical analysis was performed using SAS software MINITAB and averages were compared by Duncan's test at 1%. Results and discussion The results showed that in both drought stress and normal irrigation conditions, there was a significant differences between genotypes in terms of spike length, height, the weight of 1000 grains, grain per spike, spike per meter2, grain yield, biological yield and harvest index. The highest grain yield under irrigation conditions were belonged to genotypes 79, 95 & 120 and Yousef cultivar (with average yield 935.3 g/m2) and under drought stress conditions belonged to genotypes 95 and 120 (average yield 834.3 g/m2).The highest positive correlation under normal irrigation condition belonged to biological yield (0.94), the number of spike & grain per spike (0.51) and under drought stress conditions belonged to biological yield, the weight of 1000 grains and the number of grain with 0.96, 0.65 and 0.63 respectively. In the regression model were important traits under normal irrigation condition, including spike length, biological yield and harvest index with coefficients of determination 0.998, 0.920 & 0.995 respectively, and under drought stress condition, biological yield and harvest index with coefficients of determination 0.935 & 0.995 respectively .Overall under both environmental conditions, the genotypes 95 (with average yield 8809.7 kg/ha-1) and 120 (with average yield 8925 kg/ha-1) as the best genotypes were identified. Conclusion There are significant differences among genotypes for yield components in order to help researchers select for breeding programs could be helpful. Analysis of variance in both normal and drought conditions showed the same traits were assessed. Genotypes in terms of irrigation were significant differences in the characteristics assessed that this proves that the variation between the genotypes under different irrigation.

In order to facilitate the selection of new genotypes, diversity evaluation and analysis of relationships of effective traits on grain yield of rice in F2 populations produced by crossing of Anbarbo cultivar as mother parent with semi dwarf and highly produced by Shafagh and Najafi as paternal parents, 450 F2 genotypes with three control varieties (Anbarbo, Shafagh and Najafi) were evaluated and grain yield and 16 different agronomic traits were investigated. By comparing the descriptive statistics of the parental cultivars and the resulting F2 progenies, positive and negative transgressive segregation was observed for most traits such as yield, harvest index, peduncle length and number of fertile tillers. Dry weight of panicle, number of grains Eer plant, biological yield, number of fertile tillers and grain per panicle, harvest index, 100-grain weight, eight, panicle length and peduncle length had positive and significant correlations with grain yield. To select grain yield justifying traits, stepwise regression analysis was performed and dry weight of panicle,number of grain per plant, 100-grain weight, number of grains per panicle, first and second internode lengths were introduced into the model as the most effective traits on grain yield. Path coefficient analysis showed that the most direct and positive affecting traits were number of grains per plant (0.834), 100-grain weight (0.348) and dry weight of panicle (0.122), respectively. In this research, grain number per plant, 100-grain weight and dry weight of panicle were identified as selection indexes for improving grain yield in rice and recommended for use in rice modification projects. According to the phenotypic variation observed among F2 progenies for different traits (variation range and coefficient of variation) in this study and applying the desired segregation in breeding programs, it could be achieved new lines with the desired characteristics and increased yield in later generations. [ABSTRACT FROM AUTHOR]

To study the genetic diversity of 74 Iranian recombinant inbred lines of Neda x Ahlami Tarom under salinity stress in seedling stage, an experiment was conducted in completely randomized design with three replications and two conditions of normal culture and salt stress at Gonbad Kavous University in 2015. The seedling was evaluated in 6 dSm-1 salinity for a week, and then salt stress was increased to 12 dSm-1. Chlorophyll content, root and shoot lengths, root and shoot dry weights, leaf area, length and width of the biggest leaf, root numbers, root diameter, root density, Na+ and K+ concentrations of root and stem, Na+/K+ in shoot and root, Length, width and number of stomata and salt tolerance score were recorded. The significant differences between the lines for the studied traits showed the variation between them. The highest correlation was observed between root diameter and root surface density. The correlation coefficients were significant for seedling dry weight, leaf area and chlorophyll content and root length. In the stepwise regression, chlorophyll content and leaf area described the most significant changes. Cluster analysis based on total seedling traits divided lines into four groups andlines 11, 102, 39 and 85 were resistant to salinity stress. The results obtained from this study can identify the lines tolerated for crossing and prepare populations suitable for breeding programs. [ABSTRACT FROM AUTHOR]

Water and nitrogen stress are among the most important factors that reduce wheat yield. To study the effect of water and nitrogen stress on some morphological traits, grain yield and yield components of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) and determination the effective traits on yield, a split-plot factorial field experiment was carried out at Research Field of the School of Agricultural and Natural Resources University of Tehran, Karaj, in 2016-2017, in a randomized complete blocks design with 3 replications. The main factor was water stress at two levels, (No water stress and 40% of water requirement) and the sub factors included the combination of nitrogen fertilizer at two levels (0 and 200 kgha-1 of N) and wheat (Sivand and Pishtaz) and barley (Fajr 30) cultivars. Water and nitrogen stress reduced all traits such as 50 percent reduction in grain yield. In terms of water stress, the highest correlation was observed between grain yield and biological yield, peduncle length, number of grain per spike, spike dry weight and plant (more than 75%). Stepwise regression showed 5 and 3 varialbles significantly explain the variation of yield under normal irrigation stress conditions, respectively. Results of factor analysis revealed that factors justified 98.4% and 99.5% of total variance variation under normal and stress conditions, respectively. According to the results, biological yield was the most effective variable on grain yield under water and non-stress conditions; therefore, it could be used as a marker for yield. [ABSTRACT FROM AUTHOR]

Introduction: The pistachio (Pistacia vera), a member of the cashew family, is a small tree originating from Central Asia and the Middle East. The tree produces seeds that are widely consumed as food. Pistacia vera often is confused with other species in the genus Pistacia that are also known as pistachio. These other species can be distinguished by their geographic distributions and their seeds which are much smaller and have a soft shell. Continual advances in crop improvement through plant breeding are driven by the available genetic diversity. Therefore, the recognition and measurement of such diversity is crucial to breeding programs. In the past 20 years, the major effort in plant breeding has changed from quantitative to molecular genetics with emphasis on quantitative trait loci (QTL) identification and marker assisted selection (MAS). The germplasm-regression-combined association studies not only allow mapping of genes/QTLs with higher level of confidence, but also allow detection of genes/QTLs, which will otherwise escape detection in linkage-based QTL studies based on the planned populations. The development of the marker-based technology offers a fast, reliable, and easy way to perform multiple regression analysis and comprise an alternative approach to breeding in diverse species of plants. The availability of many makers and morphological traits can help to regression analysis between these markers and morphological traits. Materials and Methods: In this study, 20 genotypes of Pistachio were studied and yield related traits were measured. Young well-expanded leaves were collected for DNA extraction and total genomic DNA was extracted. Genotyping was performed using 15 RAPD primers and PCR amplification products were visualized by gel electrophoresis. The reproducible RAPD fragments were scored on the basis of present (1) or absent (0) bands and a binary matrix constructed using each molecular marker. Association analysis between molecular date (as independent variable) and morphological data (as dependent variable) was performed using multiple regression analysis to identify informative markers associated with the yield related traits. Multiple regression analysis was conducted using stepwise method of linear regression analysis option of SPSS. Student t-test was performed to assess significance difference between mean trait estimates of genotypes where specific markers were present and absent. Markers shown significant regression values were considered to be associated with the trait under consideration. Results and Discussion: Finally 11 primers were polymorphic and a total of 56 pieces (loci) were amplified that among these, 36 segments (64.29%) showed polymorphism with an average of 5.09% per primers and the rate of this polymorphism ranged from at least 25% for AJ05 primer up to 87.5% for OPAD02 primer. Polymorphic information content ranged from 0.095 (AJ05 and OPAD14) to 0.39 (OPC05), with an average of 0.23. Stepwise regression analysis between molecular data and traits was performed to identify informative markers associated with yield component traits. Nineteen RAPD fragments were found associated with six yield related traits. Some of RAPD markers were associated with more than one trait in multiple regression analysis that may be due to pleiotropic effect of the linked quantitative trait locus on different traits. However, to better understand these relationships, preparation of segregating population and linkage mapping is necessary. Also, these results could be useful in marker-assisted breeding programs when no other genetic information is available. Conclusion: This investigation on molecular markers associated with yield traits in Pistachio has provided clues for identification of the genotypes with higher yield value. In breeding programs selection of quality material is often a time-consuming process, and thus marker-assisted selection could be of great useful in identification of promising genotypes with high value of yield traits. Some of RAPD markers can be used for elite selection of Pistachio, particularly when no other genetic information like linkage maps and quantitative trait loci are available for the species. The applications of the RAPD approach enable us to predict positive correlation between data generated by molecular markers and studied traits. Also, the marker–trait association identification will play an important role in plant MAS/QTL breeding programs, especially in plants where genetic information such as linkage map and QTL is not available.

To study the effect of potassium sulfate on seed yield, yield components and traits affecting seed yield of late maturing corn, a split split plot experiment using a randomized complete block design with three replications was carried out in Kashan Desert Research Station. Irrigation levels consisted of complete irrigation and cutting off irrigation at panicle emergence and seed filling stages which were considered as the main factor, three levels of potassium sulfate 200 (recommendation based on the soil analysis), 245 and 290 kg.ha-1 as the subplot, and two single cross of corn, KSC 700 and 704, as sub-sub plots. Effect of irrigation on traits like seed number per row, 1000 seed weight, biological yield, relative water content and relative water loss were significant. The effect of cultivar on all traits, except relative water loss, and the effect of fertilizer on all traits, except number of rows per ear, were also significant. All of the KSC700 traits, except plant highest were better than those of cultivar KSC704. The highest values for the most traits were obtained in full irrigation condition, applying potassium sulfate at the rate of 290 kg.ha-1 for KSC 700. Cutting off irrigation at the panicle emergence of KSC 900 and seed filling of KSC 704 did not cause significant reduction in seed yield. Highest correlation of grain yield were obtained with number of kernels per row, 1000 grain weight and harvest index. Stepwise regression results showed that number of rows per ear, number of kernels per row and 1000 grain weight in KSC 700, and biological yield and harvest index in KSC 704 justified 98.7 and 98.5 percent of changes, respectively.

To evaluate relationship between grain yield and its components, two series of wheat`s substitution lines including substitution lines of ‘Timstein’ into genetic background of ‘Chinese Spring’ and ‘Red Egyptian’ into genetic background of ‘Chinese Spring’ and their parents were tested in a randomized complete block design with four replications under water-stress and non-stress conditions in a greenhouse in 2014. Stepwise regression analyses showed that yield components contributions for seed yield variation were not similar under water-stress and non-stress conditions. So that, under non-stress condition biological yield and harvest index and under water-stress condition the number of seeds per spike and number of spikes explained a higher percentage of variations for grain yield. Biological yield and harvest index were entered into model in three cases out of four regression analyses (two substitution lines series and two conditions) and thus it was deduced that these two traits are the most stable traits in explaining the variations observed for seed yield.Path coefficient analysis showed that biological yield and harvest index had direct and equal effects on seed yield at non-stress condition for two substitution line series. The highest direct effects on seed yield under stress condition for ‘Timstein’ substitution line series belonged to biological yield and harvest index and for ‘Red Egyptian’ substitution lines belonged to the number of seeds per spike and number of spikes. Cluster analysis, based on Ward method and by using Euclidian distance, classified two substitution line series under water-stress and non-stress conditions in three groups.

To investigate relationships among physiological traits of 20 rapeseed cultivars, an experiment was conducted at the Research Farm of Agricultural Faculty of Shirvan in Northern Khorasan in Iran, in 2014-2015. The experiment used was a randomized complete block design with four replications. Results showed that there were significant differences among cultivars for seed and biological yield, the number of pod/plant and seed/pod, 1000 seed weight, harvest index, days to germination, seedling, rosette, shooting, flowering time, end of flowering, pod formation time, end of pod formation, seed filling time and physiological maturity among the traits of rapeseed under study. The highest yield belonged to Traviata (513.56 g/m2) but did not have significant difference with Kodiak, Bilbao, L72 and SW102. The lowest yield belonged to Shirali cultivar (344.41 g.m-2) but it also did not have significant difference with Zarfam and Sarigol cultivars. Positive and significant correlation was observed for seed and biological yields, number of pods/plant and seeds/pod, seed weight, harvest index, the number of days to flowering, flowering end, beginning pod formation, ending pod formation, beginning seed filling, plant height and seed filling rate, but correlations were negative between seed yield and seed filling period and day to emergence and rosette. According to stepwise regression, seed yield was considered as dependent variable and other traits as independent ones. Positive direct effects of harvest index and biological yield and also positive indirect effect of biological yield on number of pod/plant and positive indirect effect number of pod/plant on harvest index were the traits that can be used for selection of high yielding genotypes. Path analysis revealed that traits like seed weight and seed number per unit, seed number and seed weight are its determiners of seed yield. The results also showed that seed filling rate is more effect than seed filling period in determination of seed weight. Regression analysis also showed that by increasing temperature, seed filling period was decreased by 1.54 days and seed filling rate increased 0.004 mg/grain.day-1 centigrad-1. Based on these results it could be concluded that genotypes varied significantly for the rate and duration of seed filling.

Estimation of correlation coefficients can accelerate walnut breeding programs and provide the ability to improve other traits along with targeted breeding traits. For this purpose, data obtained from two-year morphological evaluation of 325 screened genotypes from Fars, Mazandaran and Ilam provinces were used to study the correlation between morphological traits. In addition, in order to study the correlation between biochemical and morphological traits, biochemical characteristics of 52 superior genotypes out of 325 screened genotypes were evaluated for one year. Based on the results, a linear and strong relation was observed between phenological traits especially budbreak and harvest date. Yield had a positive and strong correlation with budbreak date (0.58**), nut weight (0.64**), kernel weight (0.46*), nut size (0.56**) and lateral bearing (0.53**) and a negative correlation with kernel color (-0.38*). Based on the result of stepwise regression analysis, nut weight, lateral bearing and nut size index were the main components of walnut yield. Correlation study between biochemical traits with altitude and morphological traits showed that oil and protein percentage of walnut kernel was not affected by the physical characteristics of the nut (nut and kernel size and weight). In Contrast, the oil and protein content increased with increasing altitude. A strong and negative correlation was observed between MUFA and PUFA. Also, PUFA: SFA ratio negatively correlated with shell thickness. [ABSTRACT FROM AUTHOR]

In the current study, the genetic variability and effect of some agronomic traits on grain yield of 218 Iranian wheat landraces were evaluated under normal irrigation and drought stress conditions employing alpha-lattice design with two replications on the research field of Agronomy and Plant Breeding at the University of Tehran during the year of 2016-2017. Results of data analysis of variance demonstrated that there were significant differences among landraces in the investigated traits including phonologic and physiologic traits, yield and yield components in both conditions. According to descriptive statistics results, the highest phenotypic variation of landraces observed in seed number per spik e, and the least variation in spik e weight. The findings on phenotypic correlations, stepwise regression, and path coefficient analysis sustain the important role of spik e weight, seed number per spik e and thousand grain weight in the grain yield in both normal irrigation and rain-fed conditions. In addition, considered traits had the highest impact on the grain yield directly and indirectly under both conditions. The result of principle component analysis presented a positive correlation between the first component and seed number in both conditions, while the second component had a positive relationship with phonological traits in normal irrigation and leaf greenness in rain-fed conditions. [ABSTRACT FROM AUTHOR]

In order to investigate the genetic diversity of 65 lines of pepper, collected from different regions of the country and also from China and the International Research Center for Vegetables (AVRDC), a randomized complete block design with 3 replications was done. Results of analysis of variance showed a significant difference among genotypes at 1% probability level for all traits. Based on the mean comparison of different traits using Tukey's method at 5% probability level, genotypes 3095, 0013 and 26-6 were better in terms of yield and characteristics associated with marketable products. To determine the genetic distance and grouping of genotypes, factor and cluster analysis performed. To understand the internal relations of traits and to determine the group of variables with the highest correlation, factor analysis performed using principal component analysis were through varimax rotation. In these analysis, four independent factors justified 74.7% of the variation. Cluster analysis done using Ward method, and the lines were gathered into six different groups. So that, this grouping was associated with geographic distribution of lines and some of morphological traits that associated with marketability. Results of stepwise regression showed that three traits of stem diameter, stem length and number of fruits per plant had the greatest effect on fruit yield. To evaluate the direct and indirect effects of these traits on fruit yield, Path analysis performed. Results showed that the three mentioned traits had direct effect and indirect effect of these traits was very low. Given that in this experiment lines under study showed significant differences in terms of genetic variability for traits under evaluation. It was concluded in order to benefit from heterosis, selection of superior genotypes with greater genetic distance from each other can be useful in pepper hybrid variety production. [ABSTRACT FROM AUTHOR]

To calculate correlation coefficients and path analysis of some traits related to grain yield, 15 genotypes of safflower were studied under non-stress and drought stress conditions at two different sites (with 10 meter distance) in the field of College of Agriculture of Lorestan University, Iran. Each experiment was conducted in a randomized complete block design with three replications. Analysis of variance showed that there were significant differences among the genotypes for all measured traits and yield in both stress and non- stress conditions. By using stepwise regression, best model was estimated for the two conditions. Sequential path analysis of the correlation between grain yield and other traits showed that days to start flowering, 1000-seed weight and stem diameter had direct effects on grain yield under non-stress conditions, while under drought conditions, seed weight per plant and 1000-seed weight had direct and positive effects on grain yield. Thus, to obtain high yielding varieties of safflower under drought stress condition, we showed attempt to select varieties with high seed weight per plant.

به‌منظور بررسی عملکرد و اجزای آن تحت تنش خشکی آزمایشی در قالب طرح بلوک کامل تصادفی با سه تکرار و ده تیمار در دو شرایط آبیاری معمول و تنش خشکی در سال 1390-1389 در مزرعه پژوهشی دانشکده کشاورزی بیرجند به اجرا در آمد. صفات موردبررسی شامل تاریخ 50 درصد گلدهی، عملکرد دانه، عملکرد بیولوژیک، وزن هزار دانه، شاخص برداشت، طول غلاف، تعداد دانه در غلاف، تعداد شاخه فرعی، تعداد غلاف در ساقه اصلی، تعداد غلاف در شاخه فرعی و تعداد کل غلاف در بوته بود. نتایج حاصل از مقایسه میانگین نشان داد که ژنوتیپ‌های هایولا 308 و لیکورد دارای بیشترین عملکرد دانه در شرایط معمول و ژنوتیپ‌های هایولا 308 و مودنا دارای بیشترین عملکرد دانه در شرایط تنش بودند. نتایج تجزیه همبستگی نشان داد که در شرایط معمول عملکرد دانه با عملکرد بیولوژیک و در شرایط تنش عملکرد دانه با عملکرد بیولوژیک، شاخص برداشت، تعداد غلاف در شاخه فرعی و تعداد کل غلاف در بوته در سطح احتمال 1 درصد همبستگی دارند. تجزیه رگرسیون گام‌به‌گام نشان داد که در شرایط معمول عملکرد بیولوژیک و در شرایط تنش شاخص برداشت تأثیرگذارترین عوامل بر عملکرد دانه بودند. تجزیه به عامل‌ها نشان داد که چهار عامل در شرایط معمول 85 درصد و در شرایط تنش 86/6 درصد از کل تغییرات واریانس را توجیه نمودند. به‌طور کل معلوم شد که ژنوتیپ‌ هایولا 308 و لیکورد دارای عملکرد دانه بالایی در هر دو شرایط آبیاری بود، اما ژنوتیپ مودنا تنها عملکرد دانه بالایی در شرایط تنش داشت.

Introduction: Saffron is one of the most important economic plants in the Khorasan province. Awareness of soil quality in agricultural lands is essential for the best management of lands and for obtaining maximum economic benefit. In general, plant growth is a function of environmental factors especially chemical and physical properties of soil (20). It has been demonstrated that there was a positive and high correlation between soil organic matter and saffron yield. Increasing the yield of saffron due to organic matter is probably due to soil nutrient, especially phosphorous and nitrogen and also improvement of soil physical quality (6, 28, 29). The yield of saffron in soils with high nitrogen as a result of vegetative growth is high (8). Shahandeh (6) found that most of the variation of saffron yield depends on soil properties. Due to the economic importance of saffron and the role of soil properties on saffron yield, this research was conducted to find the relationship between saffron yield and some soil physical and chemical properties, and to determine the contribution of soil properties that have the greatest impact on saffron yield in the Ghayenat area. Materials and Methods: This research was performed in 30 saffron fields (30 soil samples) of the Ghayenat area (longitude 59° 10΄ 10.37˝ - 59° 11΄ 38.41˝ and latitude 33° 43΄ 35.08˝ - 33΄ 44΄ 02.78˝), which is located in the Khrasan province of Iran. In this research, 21 soil properties were regarded as the total data set (TDS). Then the principal component analysis (PCA) was used to determine the most important soil properties affecting saffron yield as a minimum data set (MDS) and the stepwise regression to estimate saffron yield. To estimate the yield of saffron in stepwise regression method, saffron yield was considered as a dependent variable and soil physical and chemical properties were considered to be independent variables. Results and Discussion: According to the PCA method, among the 21 studied properties, 7 out of them including calcium, iron, zinc contents, sand, calcium carbonate equivalent percent, mean weight diameter of aggregates (MWD) and manganese (Mn) had the higher Eigenvalues. Therefore, the above properties were introduced as the most important soil properties in saffron fields. Calcium carbonate had the negative effect on the availability of micro-nutrients (26). Christensen et al. (15) found that by increasing the calcium carbonate in soil due to high pH and formation of insoluble components, the uptake of micro-nutrients is especially limited. The results of stepwise regression method (equation 1) showed that soil acidity (pH), zinc content, bulk density, MWD, iron content, salinity (EC), organic carbon and available potassium in soil were the most important properties that affect the yield of saffron, so that the determination coefficient (R2) of the regression model was high (Table 2) and it can explain 74% of the variation of saffron yield. Y = 6924.51 – 1187.31 pH – 89.65 EC + 71.6 Fe – 826.02 Zn + 471.55 OC, + 5490.96 K + 1353.56 BD + 752.82 MWD (1) where Y: saffron yield (kgha-1), pH: soil acidity, EC: electoral conductivity (dSm-1), Fe: iron concentration (mgkg-1), Zn: zinc concentration (mgkg-1), OC: organic carbon (%), K: soil potassium (%), BD: soil bulk density (Mgm-3), and MWD: mean weight diameter of aggregates (MM). Based on the absolute values of standard ß in the regression model (Table 3), pH value and then after Zn concentration had the most effect on saffron yield. In general, responses of different plants to soil pH is varied, and saffron grows satisfactory in pH = 7.8 (5). Soil pH influences the uptake of soil nutrients by plants (15), so that this parameter had the most effect on saffron yield and by increasing the soil pH, the yield of saffron decreases. According to the regression model, Zn concentration was the second parameter in saffron yield. Zn has the important role in structure of plant enzymes (30). After these 2 parameters, Bd, MWD, Fe concentration, EC, Organic carbon and K concentration in soil had more effect on saffron yield (Table 3). Conclusion: According to both PCA and regression methods, the concentration of iron and zinc and MWD were determined as the important and effective soil properties on saffron yield in the Ghayenat area. In addition, soil pH in stepwise regression method and calcium carbonate in PCA method were determined as the effective properties on saffron yield. Therefore, it is suggested that the parameters of Zn, Fe, and MWD along with soil pH and calcium carbonate which were regarded individually in two methods, were considered as the most soil properties in saffron yield.

In order to evaluate the productivity of 20 bread wheat promising lines using multivariate statistical methods, an experiment was conducted based on a randomize complete block design under terminal moisture stress, in 2011-2012. Factor analysis showed that the three first factors explained 66% of total variance. Plant height, peduncle length, 1000 kernel weight, harvest index, biological yield, peduncle weight and shoot weight were detected as the most effective traits on the grain yield. In addition, the bread wheat lines number 17, 14 and 15 out-performed the other lines under the terminal moisture stress condition. Cluster analysis using Ward method grouped the lines in four clusters, i. e. the first cluster consisting the best lines with the highest grain yields. Discrimination function analysis confirmed the clustering results. The results of stepwise regression analysis indicated that the days to 50 percent physiological maturity, plant height, total leaf area, harvest index and biological yield were the most effective traits on grain yield under the conditions of present experiment (i.e. they explained 86 percent of the yield variance). Results of path analysis showed that the harvest index and biomass yield left the maximum direct positive effects on the grain yield. The latter traits can, therefore, be hired for indirect selection of drought tolerant bread wheat lines under terminal moisture stress condition. The line 17 with a greater earliness and the maximum relative grain yield was recognized as the most suitable line under the conditions of the present experiment

One way to decreases the damage caused by cavitation in spillways is aeration flow using aerators. The required air flow of aerator is one of the most important factors in their design. In this study, to estimate the required air flow of spillway aerators four methods were applied including of stepwise regression, Pfister empirical method, neural network (based on Levenberg- Marquardt algorithm) and the combination of fuzzy-neural (ANFIS). In order to perform of modeling, 914 experimental data on physical model of Clyde Dam spillway and 12 data of Azad Dam related to conducted tests by Water Research Center on Azad dam hydraulic model were gathered. However, the performance and error of these methods were investigated after calculating the required air flow of aerators. The results showed that the combination of fuzzy-neural has the best performance with a root mean square error (RMSE) and correlation coefficient (R) about 0.0194 and 0.968, respectively. In addition, artificial neural network, stepwise regression and Pfister empirical methods had a root mean square error equal to 0.0538, 0.0596 and 1.98, respectively.

To evaluation the response of some maize hybrids to water deficit stress, a field experiment in 2010 was conducted using a split-plot plan on the basis of complete randomized block design with four replications at the Agricultural Research Station, University of Tabriz (Khalatpoushan). Main plots consisted of three different irrigation regimes (non-stress, mid-stress and sever-stress) and sub plots of 14 maize hybrids. Results showed significant differences among hybrids and irrigation regimes for all traits studied. Analysis of variance revealed significant differences among hybrids and also irrigation levels for all traits except ear diameter. The best model for stepwise regression based on all traits at the average of conditions, indicated that four responsible traits like number of rows per ear, 300-grain weight, number of grains per row and number of leaves per plant remained in model, which justified 83 percent of the total variations in yield performance. The path analysis showed that the number of rows per ear had the highest direct effect on yield. Based on principal component analysis the first component had a major factor on the weight of 300 seeds, plant height, ear length, flag leaf area, ear diameter and corn cob diameter and the second component had a big factor on plant dry weight, number of kernels per row, number of leaves per plant, number of rows per ear and grain yield. Principal component analysis (PCA), based on all of traits studied determined two principal components that could justify the 78 percent of vaiations. In this research the first component named as the growth-morphological factor and second component named as the yield factor.

Soil carbon sequestration and storage is one of the important methods to reduce the atmospheric carbon dioxide and mitigating climate change effects. Therefore, with identification of the effective factors on carbon storage can be helpful to improve soil fertility and environmental protection. Therefore, this study was conducted to investigate the effects of some soil physical factors on soil organic carbon (SOC) storage content in drylands of Sarfiroozabad watershed, Kermanshah province, Iran. So, the watershed was separated into homogeneous zones and soil sampling was performed using a randomized systematic method in the units. The samples were transported to the laboratory and texture, TNV%, gravel% and organic carbon were analyzed to determine the SOC storage. Then, using stepwise regression, cluster and factor analysis, the effective factors on carbon storage were studied. The results of cluster analysis showed three variables such as TNV%, Silt% and SP%, are effective on SOC storage and the regression model with this three variables can predict 33 percent of the soil carbon storage variability with a correlation coefficient of 0.574. Also, cluster analysis to predict the effects of physical factors on carbon storage is important with EF= 0.32. Therefore, it was proven that the soil factors are more effective than climate and topography factors to predict SOC storage. It shows that improving the soil conditions and correct management, to keep soil carbon stocks should be given more attention.

Using multivariate statistical methods in evaluation of various traits in several genotypes has caused the discovery of different aspects of agronomic crops’ traits. In order to study diversity and interrelationships of yield and yield components of rapeseed, 36 genotypes of rapeseed were used in a 6 × 6 simple lattice design layout with two replications. Results of primary analysis of variance indicated that it was possible to analyze the dataset via randomized complete blocks design. In general, 13 traits, which were related to yield and yield components, were evaluated in this investigation. Results of dataset analysis showed that there was considerable variation among the genotypes. Seed yield of rapeseed had positive and significant correlation with 1000-seed weight, harvest index, number of secondary branches in plant and maturity period. In stepwise regression of yield with other traits, the 1000-seed weight and days to end of flowering described most of the variations of seed yield. Also, results of path analysis indicated that 1000-seed weight and days to end of flowering had direct and remarkable effect on seed yield. Cluster analysis and multivariate analysis of variance divided the genotypes into five distinct groups. Based on seed yield and 1000-seed weight, the genotypes of fifth cluster and according to highest number of pods per plant, the genotypes of third cluster were considerable. In general, the most important trait which affected seed yield of rapeseed was 1000-seed weight, which could be used for indirect selection of seed yield in segregating generations.

به منظور مطالعه اثر تنش خشکی بر صفات مورفولوژیک، عملکرد و اجزای عملکرد ذرت شیرین، تحقیقی در مزرعه مرکز تحقیقات کشاورزی و منابع طبیعی استان خراسان رضوی (ایستگاه طرق-مشهد) در سال 1389، در قالب آزمایش اسپلیت پلات فاکتوریل با طرح پایه بلوک­های کامل تصادفی و با چهار تکرار انجام شد. در کرت­های اصلی مقادیر مختلف آبیاری در سه سطح (شامل آبیاری کامل، تنش ملایم و تنش شدید به ترتیب بر اساس 100، 80 و 60 درصد ظرفیت زراعی) و در کرت­های فرعی رقم (Ksc403، مریت و آبسیژن) و روش کاشت (روی پشته و کف جوی) قرار گرفتند. در این آزمایش عملکرد و 17 صفت موثر در عملکرد مورد بررسی و تجزیه و تحلیل قرار گرفت. نتایج تجزیه واریانس نشان داد که بین هیبریدهای مختلف از نظر صفات مورد اندازه گیری تفاوت معنی­دار وجود دارد. همچنین اثر تنش خشکی بر صفات مورد ارزیابی معنی­دار بود. در این آزمایش صفات طول بلال، تعداد برگ بالای بلال اصلی و تعداد ردیف دانه در بلال به ترتیب دارای بالاترین همبستگی مثبت با عملکرد دانه بودند. با توجه به نتایج به دست آمده از نتایج رگرسیون گام به گام و تجزیه به مؤلفه‌های اصلی، می­توان نتیجه گرفت که صفات وزن هزار دانه، طول دوره گرده افشانی تا کاکل دهی و تعداد دانه در بلال تعیین کننده محدودیت­های ذرت شیرین در تولید دانه هستند.

Iran is one of arid and semi-arid regions of the world. Wheat as a strategic agricultural products faces water deficiency in most areas of the country. Therefore, identification of the resistant varieties to drought stress is one of main aims for breeders. To assess effect of drought stress at heading on 72 spring wheat recombinant inbred lines derived from American Yecora Rojo (high yielder, dwarf and early maturity) as paternal parent and Iranian No. 49 line (tall and late maturiting) as maternal parent cross were studied. The experiment was conducted at the Research Station of the University of Tabriz using a randomized complete block design with two replications during 2009 growing season. Based on the results from combined analysis of variance significant difference was observed among lines for all of traits studied, except for harvest index, grain number per spike and days to heading. There was significant difference between normal and drought stress conditions. Since the interaction between line and conditions was insignificant for all traits, it does therefore, provide the possibility of comparing the lines without regard to irrigation levels. Based on the means of, the traits it was found that the lines 96, 122, 123 and 155 were superior. MP, GMP and STI indices were recognized to be suitable indices to identify superior lines. With respect to these indices, lines 96, 122, 123, 138, 149 and 155 were found superior as compared with remaining lines. Based on stepwise regression analysis of grain yield with other traits, respectively grain number per spike, number of spikes/m2 and 1000 kernel weight were inserted into final model as effective variables on grain yield, which made 81/9 percent of the grain yield variation. Path analysis of grain yield and related traits, based on stepwise regression, demonstrated the significant positive direct effect for grain number per spike, number of spikes/m2 and 1000 kernel weight on grain yield. Cluster analysis, also showed that, lines under study were grouped into two clusters; superior lines for studied traits assigned to group one.

Emission of carbon dioxide via human activities is known as the main cause of global warming. Appropriate forest management practices can have effective role to mitigate carbon emission as well as adsorb atmospheric carbon. The present research was carried out to investigate the effect of 35 years old Common ash (Fraxinus excelsior L.), Chestnut-leaved Oak (Quercus castaneifolia C.A.Mey), Norway spruce (Picea abies L. Krast) and Black pine (Pinus nigra Arn.) plantations on soil carbon sequestration in Dehmian plantation. Systematic soil sampling was done randomly. Totally 54 soil samples were taken from the top soil layers (0 – 10 and 10 – 20cm depths) in four plantations. Soil texture, pH, bulk density, electrical conductivity, organic carbon and total nitrogen were measured in the laboratory. Analysis of variance indicated that the amount of soil carbon sequestration of softwood plantations stands increased in comparison with hardwood ones. Results showed that the amount of soil carbon sequestration in Norway spruce stand (124.27 ton/ha) was significantly (P

Adaptation of thirty rice genotypes was studied in a completely randomized block design experiment with 3 replications for two cropping seasons (2005-2006) in Astara. Analysis of variance showed that differences among the years for the most of traits were not significant where as there was a significant difference among the genotypes and genotype by year interaction. Correlation coefficient of the traits under study showed that grain yield had a positive and significant correlation with number of tiller per plant, paddy yield and harvest index. Stepwise regression analysis revealed that the paddy yield per plant and panicle length had a positive and significant effect on the grain yield. Cluster analysis of genotypes in these grouped genotypes into three categories. Two years of experiment showed these lines producing higher yields, were better adapted to Nemat, line 338, Sangtaroom, Dorfak, Mehr and line 6 fell into the second group.

Relationships between grain yield and yield components in some hull-less barley lines were studied in experiment conducted in a randomized complete block design with 4 replications at the Research Station of Agriculture of Gorgan, Iran. During growth season several characteristics including plant height spike length, number of spike per m2, biological yield, number of total tillers, number of fertile tillers, number of kernel per spike, number of spikelet per spike, relative water content (RWC), coefficient of membrane stability (CMS), flag leaf area, Na/K ratio, grain yield, 1000 kernel weight and harvest index were measured. Results showed that stepwise multivariate analysis was the best suitable model in evaluating of the yield. Path analysis showed that correlation among characteristics which remained in the model was broken into direct and indirect effects. The results derived from correlation and path analysis indicated that almost 70% of the yield increase was due to the direct effect of 1000 kernel weight. Number of kernel per spike was positively significant and number of fertile tillage was also found to have positive and significant direct effect on yield, but number of fertile tiller indirectly affects by higher 1000 kernel weight.

Because of several radiometric errors, precise estimation of forest stand volume based on spectral indices is not achievable. In contrast to spectral indices, textural indices are more consistent dealing with these errors. In this research, estimation of forest stand volume based on textural indices was studied. For this aim, 150 plots were collected using systematic random design. Green, red and near infra red bands were used. Textural indices included second moment, contrast and homogeneity extract by different window size. Appropriate band, index and window size were chosen by stepwise regression. Based on this analysis, near infra red band, homogeneity index and 31×31 pixel window size were selected. RMSE and bias of estimation was 43 and 2 percent, respectively. Although, estimation accuracy of forest stand volume by textual indices was suitable for mapping purposes, however, its application in forestry operations needs more researches.