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Amid urbanization, studying leaf functional traits of woody plants in urban environments is essential for understanding how urban green spaces function and how they can be effectively managed sustainably. In this study, we investigated the effects of different growing conditions on the morpho-physiological traits of Populus laurifolia and Ulmus pumila across five contrasting urban sites. The leaf area (LA), leaf length (LL), leaf width (LW), leaf biomass (LB), specific leaf area (SLA), leaf chlorophyll concentration, chlorophyll fluorescence parameters, leaf water potential at predawn (Ψpd) and midday (Ψmd), leaf performance index (PIabs), and phenotypic plasticity index (PPI) were compared across five contrasting urban sites. The soil chemical and physical properties were also compared between sites. There were significant differences in soil physicochemical characteristics between sites. We found significant effects of site on most of the morpho-physiological traits measured, except for Ψmd. The leaf chlorophyll concentration of P. laurifolia and U. pumila varied significantly between sites. The Ψpd was significantly different between years and sites. In U. pumila, the mean PPI for morphological traits (0.20) was lower than that for physiological traits (0.21). In conclusion, we revealed significant variations in the morpho-physiological traits of P. laurifolia and U. pumila across the five urban sites. Hence, long-term, large-scale studies are recommended to examine how diverse species respond to different urban growing conditions and to include other ecologically important plant traits for a better understanding of urban trees in a changing environment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, the physico-chemical quality of the water in the Midia coastal area, the Tasaul Lake and the Siutghiol Lake water bodies were analyzed, as integrated sites in the territory of the North Dobrogea FLAG. This study allows establishing the state of favourability of the aquatic ecosystem, focusing on the chlorophyll content as the basis of the trophic level. The premise of a stable ecosystem induces the possibility of developing natural fish resources. An essential attribute in the context of preserving natural heritage and increasing the attractiveness for fishing activities, is the need to evaluate the qualitative and quantitative profile of the phytoplankton and, respectively, the eutrophication indicators. If aquaculture activities will be developed in the analyzed areas in the future, they could increase the economic value of the Romanian sector of the Black Sea. The biological analyzes of the water quality are the basis of the substantiation of some methods of its determination and evaluation. Thus, testing the concentration of chlorophyll, the classes of algae and the photosynthetic activity, are useful for the evaluation of eutrophication in the aquatic environment, but also for the evaluation of productivity in the surface waters studied. At the same time, the determination and evaluation of the physical and chemical parameters of water quality allowed the realization of some correlations with the structure of the biota. In this sense, the analysis methods are based on the use of modern equipment based on real time (in situ) determinations. [ABSTRACT FROM AUTHOR]

Introduction: One of the most important problems threatening agriculture is water deficit stress in many regions of the world. Water deficit stress could result in a decrease in yielding or death of a wide range of crops. In Iran, like other arid and semi-arid regions, forage quality and production have decreased due to the occurrence of frequent water stress. Restriction of water resources, especially in arid and semi-arid regions where agricultural systems depend on supplementary irrigation, has become the most important problem of fodder production. Persian clover (Trifolium resupinatum L.) is a forage legume cultivated in the temperate region of world; it is of great value for livestock feed, soil improvement, and reclaiming disturbed land because of its nitrogen-fixing capability. The purpose of this research, was evaluate the effect of water deficit stress on the physiological and qualitative traits of fodder of Persian clover. Materials and methods: An experiment was carried out during the 2016 and 2017 cropping seasons as a randomized complete block design at the Research Farm of Tarbiat Modares University. Experimental treatments included water deficit stress at four levels. The tested treatments included water deficit stress at four levels (irrigation after reaching the levels of 80, 60, 40 and 20% available moisture). Irrigation of all treatments was carried out at the level of 70% of available water until the start of stress in the final stages of vegetative growth of the second cut. To measure the effects of water deficit stress on physiological traits physiological indexes were recorded during the first 10 days of stress treatment, every day. The clovers were harvested at about 20-25% flowering stage. After drying, they were transferred to the laboratory to determine the quantitative and qualitative feed yield. Based on Bartlett's test results, the experiment's dependent variables had the same trend. Results and discussion: The results show that the irrigation regime had a significant effect on all traits. Irrigation treatments at 80 and 60% of available water had the highest dry matter yield, and delaying irrigation until 40 and 20% caused a 19% and 36% significant decrease in this trait. Also, stress at the level of 20% caused a 27% decrease in fodder protein, a 10% increase in acid detergent fiber and neutral detergent fiber, and finally, an 16% reducing relative feed value. Evaluation of physiological traits in the first ten days of the beginning of water stress showed a continuous increase in leaf temperature from 30.5 to 34 °C, and 49, 50, and 15% decrease in photosynthesis rate, stomatal conductance, and SPAD index, respectively. It Also reduces the concentration of chlorophyll a and b 25 and 40 percent. The return of increased leaf temperature and reduced stomatal conductance due to the discharge of 80% moisture was fast to the initial level, but other traits slowly approached the value before the stress. It seems that returning to initial values at levels of 80 and 60 is easily possible for the plant, but with the increase in the intensity of stress, the damage of dehydration is slowly compensated. Conclusion The experiment results showed that the photosynthesis rate and other physiological traits of Persian clover significantly react to the soil's decreased available water. In most physiological traits, irrigation after the available soil moisture reached 60% caused a relatively quick return to the initial value. There was no significant difference in fodder yield in the 80% and 60% irrigation treatments. When the available soil moisture reached 40%, the physiological traits showed a greater decrease than before. It seems that some damages to physiological traits are irreparable to such an extent that they eventually lead to a drop in yield or a decrease in the quality of Persian clover fodder. Finally, it is not necessary for clover irrigation at levels of more than 60% of available water, taking into account the more quality of forage in the level of 60% (about 1.5% of insoluble fiber, and 11% feed value), considering the water conditions of the country. [ABSTRACT FROM AUTHOR]

In this paper, the spatio-temporal variations of Yemen, Oman and west coast of India upwelling are studied using wind and Sea Surface Temperature (SST) based upwelling indices. The relative contributions of offshore Ekman transport and Ekman pumping are compared in these upwelling regions. It has been found that offshore Ekman transport is the more dominant mechanism in coastal areas of Oman from 17°N to 21°N with upwelling indices reaching up to 3–4 m2/s during June-July while for the Yemen coast (13–16.5°N), Ekman pumping is stronger. The west coast of India has much weaker upwelling during the southwest monsoon. Offshore Ekman transport is the main mechanism for upwelling activity during the southwest monsoon for the west coast of India. A combined upwelling index was developed, adding the contributions of Ekman transport and integrated Ekman pumping. Chlorophyll data from 1998 to 2017 showed an increase in chlorophyll concentration during southwest monsoon season for all three upwelling regions. The maximum increase in southwest monsoon chlorophyll was observed for northern Yemen (15–16.5°N) with an increase of 10–20 times. This is followed by coastal region of Oman (17–19°N) and southern part of west coast of India (8–10°N). [ABSTRACT FROM AUTHOR]

Remote-sensed vegetation indices (VIs) have emerged as essential tools for retrieving forest chlorophyll concentration. Although VIs are widely used, some concerns regarding VIs for estimating chlorophyll remain to be addressed, such as saturation effect, leaf area index (LAI) disturbance, and soil brightness influence. Currently, a systematic study on such performance evaluation of chlorophyll-related VIs considering these issues is still insufficient. This study coupled two radiative transfer models, the PROSPECT model and the LESS model, to simulate Eucalyptus monocultures with different chlorophyll content and systematically evaluated the 18 broad-band VIs’ ability in chlorophyll estimation at different scales. Our results indicate that most VIs designed for chlorophyll estimation were relatively resistant to saturation, except for SIPI and some classical VIs (e.g., NDVI and DVI), which were insensitive to chlorophyll decreases and tended to reach saturation quickly (when leaf chlorophyll content (LCC) exceeded 40 ug/cm2). The relationships between NDVI, SR, DVI, and LCC were easily influenced by soil brightness and LAI. S2REP, MTCI, TGI, TCARI, and EVI were insensitive to soil brightness when estimating LCC. Overall, S2REP was best at quantitatively retrieving chlorophyll and resisting interference from other factors. For practical applications, our study suggests that it is preferable to use S2REP for LCC estimation when the red-edge band is available; otherwise, CVI can be used instead. The judicious utilization of VI can effectively depict chlorophyll levels and improve the understanding of vegetation response to climate change. Our findings provide the necessary information for the selection of specific VIs tailored to specific vegetation parameters.

Amid urbanization, studying leaf functional traits of woody plants in urban environments is essential for understanding how urban green spaces function and how they can be effectively managed sustainably. In this study, we investigated the effects of different growing conditions on the morpho-physiological traits of Populus laurifolia and Ulmus pumila across five contrasting urban sites. The leaf area (LA), leaf length (LL), leaf width (LW), leaf biomass (LB), specific leaf area (SLA), leaf chlorophyll concentration, chlorophyll fluorescence parameters, leaf water potential at predawn (Ψpd) and midday (Ψmd), leaf performance index (PIabs), and phenotypic plasticity index (PPI) were compared across five contrasting urban sites. The soil chemical and physical properties were also compared between sites. There were significant differences in soil physicochemical characteristics between sites. We found significant effects of site on most of the morpho-physiological traits measured, except for Ψmd. The leaf chlorophyll concentration of P. laurifolia and U. pumila varied significantly between sites. The Ψpd was significantly different between years and sites. In U. pumila, the mean PPI for morphological traits (0.20) was lower than that for physiological traits (0.21). In conclusion, we revealed significant variations in the morpho-physiological traits of P. laurifolia and U. pumila across the five urban sites. Hence, long-term, large-scale studies are recommended to examine how diverse species respond to different urban growing conditions and to include other ecologically important plant traits for a better understanding of urban trees in a changing environment.

Leaf Soil-Plant Analysis Development (SPAD) prediction is a crucial measure of plant health and is essential for optimizing indoor plant management. The deep learning methods offer advanced tools for precise evaluations but their adaptation to the heterogeneous indoor plant ecosystem presents distinct challenges. This study assesses how accurately deep neural network (DNN) predicts SPAD values in leaves on indoor plants when compared to well-established machine learning techniques, including Random Forest (RF) and Extreme Gradient Boosting (XGB). The covariates for prediction were based on low-cost multispectral and soil electro-conductivity (EC) sensors, enabling a non-destructive sensing approach. The study also strongly emphasized multicollinearity analysis quantified by the Variance Inflation Factor (VIF) and two independent indices, as well as its effect on prediction accuracy using deep and machine learning methods. DNN resulted in higher accuracy to RF and XGB, also performing better using filtered data after multicollinearity analysis based on the coefficient of determination (R2), root mean square error (RMSE) and mean absolute error (MAE) (R2 = 0.589, RMSE = 11.68, MAE = 9.52) in comparison to using all input covariates (R2 = 0.476, RMSE = 12.90, MAE = 10.94). Overall, DNN was proven as a more accurate prediction method than the conventional machine learning approach for the prediction of leaf SPAD values in indoor plants, despite using heterogenous plant types and input covariates. [ABSTRACT FROM AUTHOR]

Ditylenchus dipsaci is a plant-parasitic nematode with a great economic impact on bulbous crops, including garlic (Allium sativum L.), and is distributed worldwide, particularly in the Mediterranean region. Traditionally, garlic was a rainfed crop in Spain, but irrigated areas have increased during the last few decades. However, the expected climatic conditions, with longer and more intense droughts, will make it necessary to reduce the water supply to garlic crops. This poses the urgent need to select garlic cultivars more tolerant to water scarcity and that are also more resistant to plant pathogenic organisms. The aim of this work was to analyze the influence of water stress on the host response of garlic plants to D. dipsaci. The specific objectives were to evaluate the level of nematode infestation in plants from four garlic genotypes treated with a reduced irrigation regime and compare them with those of control plants not subjected to water stress. The observed results were correlated with changes in the bulb and root development, as well as in the physiological parameters (total chlorophyll concentration and proline accumulation). The effects were different depending on whether the plants were subjected to water stress before or after nematode inoculation, as well as whether the water stress was continuous or discontinuous. Garlic inter-cultivar variability also affected the obtained results. [ABSTRACT FROM AUTHOR]

Summer blooms of potentially harmful cyanobacteria are common in the Baltic Sea. Under clear sky conditions, the cyanobacterial blooms are easily detectable from space. We propose a new regional algorithm for cyanobacteria biomass estimation from satellite data in the eastern part of the Gulf of Finland, developed on the basis of field measurements in July–August 2012–2014. The multi-regression equation defines the cyanobacteria biomass as a function of the particle backscattering coefficient and chlorophyll concentration. The use of this equation provides the best performance in comparison to the linear one, which is reflected in both R2 and RMSE values (0.61 and 272 mg m−3 respectively). Unlike other algorithms, which determine only the cyanobacteria bloom area in the Baltic Sea, our algorithm allows the determination of both a bloom area and its intensity. Considering the algorithm errors, the bloom detection threshold has been shifted from the 200 mg m−3 determined by biologists to 300 mg m−3. Based on data from the MODIS-Aqua satellite ocean color scanner, the spatial and temporal variability of cyanobacterial blooms in this region from 2003 to 2022 was analyzed. Significant interannual variability of cyanobacteria biomass was revealed in the central part of the studied region, with minimum values in 2014 and maximum in 2004. The record bloom during the studied period occurred in July 2004 (the average cyanobacteria biomass was 780 mg m−3). The weakest blooms were observed in 2009, 2010, and 2014, when both in July and August, the bloom areas did not exceed 30% of the study region. [ABSTRACT FROM AUTHOR]

The use of inorganic fertilizers has become increasingly necessary due to the depletion of soil fertility. Inadequate nutrient levels in both plants and soil can be remedied with the application of fertilizers. However, to achieve optimal results, it is recommended to supplement inorganic fertilizers with organic alternatives such as biochar. Despite its benefits, the high pH of activated carbon presents a significant challenge to its use in alkaline soil. Recent studies have shown that acidified carbon can be used instead of alkaline activated carbon. Moreover, the use of biofertilizers is crucial for maintaining soil quality. The purpose of the current study was to investigate the effects of using biofertilizers, inorganic nitrogen fertilizer, and acidified carbon fertilizer in combination on fenugreek growth and chlorophyll concentrations. A pot experiment was conducted using calcium ammonium nitrate (CAN) and three levels of acidified carbon (BC) at 0, 0.75, and 1.50%, with and without the addition of biofertilizer (BF). The results revealed that 1.50CANBC + BF was the most effective supplement for improving soil characteristics such as pH, EC, and overall organic matter. The application of 0.75CANBC + BF was found to be a successful treatment for promoting fenugreek growth and enhancing nitrogen absorption. To achieve better fenugreek quality by reducing electrolyte leakage and MDA, and increasing chlorophyll levels, gardeners are advised to use 1.50CANBC + BF. However, to establish 1.50CANBC + BF as the optimal method for fenugreek growth in poor fertility and high pH soils, further experimental studies in various agro-climatic conditions are necessary.

Chlorophyll concentration relies on the plankton present on the ocean surface that is affected by climatic changes. Remote sensing applications deploy sensing devices on the ocean surface for detecting the characteristics of plankton behaviors. Such a process generates time-dependent data for analyzing the chlorophyll concentrations. This article introduced a Hybrid Chlorophyll Concentration Estimation Scheme (HC2ES) using remote sensing application data. The hybrid process was employed by using a genetic algorithm and deep reinforcement learning for data segregation and concentration analysis. The genetic process assimilated the low and high chlorophyll (sensed) data for identifying the climatic impact on vegetation. The no-concentration data was segregated by using the mutation operation of the genetic process. The mutated data was recurrently analyzed by using current and previous concentration levels (data) in the reinforcement layers, which provided further classifications on high and low chlorophyll concentrations for providing insights into remote sensing expansions. The joint hybrid process filtered the fewer concentration data preventing its analysis from identifying chlorophyll and its associated inputs. The proposed scheme was validated by using analysis rate, classification, concentration detection, and computation time. [ABSTRACT FROM AUTHOR]

More and more attention has been paid to the study of the impact of extreme climatic events on the ecological environment off the Changjiang River Estuary. In this study, the relationship between the chlorophyll concentration and ENSO (El Niño Southern Oscillation) events was studied. Several potential physical mechanisms between the ENSO and chlorophyll concentration were analyzed using observation and sensitivity experiments from a high-resolution ROMS-CoSiNE coupled model (Regional Ocean Modeling System-Carbon, Oxygen, Silicon, Nitrogen and Ecosystem) off the Changjiang River Estuary. Our results indicated that the April to August averaged chlorophyll concentration off the Changjiang River Estuary was significantly correlated with the December to February averaged ENSO indices in the previous winter. The 10 m wind speed and SST (Sea Surface Temperature) affected by an ENSO event had little effect on the chlorophyll concentration, while the discharge had a significant effect on the chlorophyll concentration off the Changjiang River Estuary, and the discharge was significantly and positively correlated with the ENSO indices. We tested the effect of interannual variations of the discharge and nutrients carried by discharge on the interannual variation in the chlorophyll concentration in the ENSO events. Two sensitivity experiments showed that when the nutrients in the freshwater discharge were kept as a constant seasonal cycle, the composite differences in the chlorophyll concentration between the positive and negative ENSO phases off the Changjiang River Estuary were reduced. When there were no nutrients in the freshwater discharge, the composite differences in the chlorophyll concentration between the positive and negative ENSO phases off the Changjiang River Estuary were reduced by one order of magnitude. The discharge can modify the stratification off the Changjiang River Estuary, and the nutrients carried by the discharge play a dominant role in determining the interannual variation of the chlorophyll concentration associated with the ENSO cycles. [ABSTRACT FROM AUTHOR]

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Several strategies have been proposed recently to reduce the accumulated harmful circumstances of intensive conventional farming practices. The adoption of conservation soil tillage and organic fertilization techniques could contribute to achieving this goal. The study was conducted over a three-year trial to assess the effects of soil tillage practices (plough; subsoil; spading) and fertilization management (inorganic vs. organic) on durum wheat growth dynamics and productivity in a Mediterranean environment. The chlorophyll concentration (CC) was evaluated using an MC-100 chlorophyll meter, and Green Area (GA) was extracted from red-green-blue (RGB) digital images acquired with a commercially available digital camera. These non-destructive low-cost methods were used to examine crop status and its reactions to climate conditions over three consecutive growing seasons in the field. A positive strong linear relationship between both CC and GA against grain yield in each growing season was identified. The study highlights that CC and GA methods are valuable tools to assess crop development under Mediterranean conditions. The results indicated that the applied conservation tillage systems, such as subsoil tillage and using the spading machine, along with organic fertilization with compost, are valuable choices in the Mediterranean basin for sustainable and higher crop production (13%) compared to the conventional traditional system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central China Normal University is the property of Huazhong Normal University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Leaf Soil-Plant Analysis Development (SPAD) prediction is a crucial measure of plant health and is essential for optimizing indoor plant management. The deep learning methods offer advanced tools for precise evaluations but their adaptation to the heterogeneous indoor plant ecosystem presents distinct challenges. This study assesses how accurately deep neural network (DNN) predicts SPAD values in leaves on indoor plants when compared to well-established machine learning techniques, including Random Forest (RF) and Extreme Gradient Boosting (XGB). The covariates for prediction were based on low-cost multispectral and soil electro-conductivity (EC) sensors, enabling a non-destructive sensing approach. The study also strongly emphasized multicollinearity analysis quantified by the Variance Inflation Factor (VIF) and two independent indices, as well as its effect on prediction accuracy using deep and machine learning methods. DNN resulted in higher accuracy to RF and XGB, also performing better using filtered data after multicollinearity analysis based on the coefficient of determination (R2), root mean square error (RMSE) and mean absolute error (MAE) (R2 = 0.589, RMSE = 11.68, MAE = 9.52) in comparison to using all input covariates (R2 = 0.476, RMSE = 12.90, MAE = 10.94). Overall, DNN was proven as a more accurate prediction method than the conventional machine learning approach for the prediction of leaf SPAD values in indoor plants, despite using heterogenous plant types and input covariates.

Ditylenchus dipsaci is a plant-parasitic nematode with a great economic impact on bulbous crops, including garlic (Allium sativum L.), and is distributed worldwide, particularly in the Mediterranean region. Traditionally, garlic was a rainfed crop in Spain, but irrigated areas have increased during the last few decades. However, the expected climatic conditions, with longer and more intense droughts, will make it necessary to reduce the water supply to garlic crops. This poses the urgent need to select garlic cultivars more tolerant to water scarcity and that are also more resistant to plant pathogenic organisms. The aim of this work was to analyze the influence of water stress on the host response of garlic plants to D. dipsaci. The specific objectives were to evaluate the level of nematode infestation in plants from four garlic genotypes treated with a reduced irrigation regime and compare them with those of control plants not subjected to water stress. The observed results were correlated with changes in the bulb and root development, as well as in the physiological parameters (total chlorophyll concentration and proline accumulation). The effects were different depending on whether the plants were subjected to water stress before or after nematode inoculation, as well as whether the water stress was continuous or discontinuous. Garlic inter-cultivar variability also affected the obtained results.

Introduction: Autumn cultivation of potato plant is very important because of meeting domestic needs of the country in winter and reducing the price of this product in the market. Cold stress in the early stages of potato growth is the most important factor that limits potato production in these areas. The yield and chemical composition of potato tubers under winter planting date and salicylic acid foliar application in Khuzestan region are very importance because one of the problems in cultivation of potato under Khuzestan conditions is insufficient growth due to dealing with high temperature at the end of the growing season in the autumn cultivation. Because few studies have been done in this regard on new cultivars of potato plant. Therefore, this experiment was performed to investigate of the tuber yield and attributes of tuber yield in potato plant. Materials and Methods: The current study was conducted in a split-split plot based on randomized complete block design with three replication in the experimental farm of the Department of Plant Genetics and Production Engineering, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran, during the crop year 2020-21. The experimental factors in this research include the date of cultivation as the main plot in three levels (25 November, 9 December, 26 December), salicylic acid foliar application as a sub-plot in two levels (0.5 mM and non-foliar application) and cultivars as sub-sub plot at three levels (including early and new cultivars Sifra, Challenger and Columba). Results and Discussion: According to the results of this experiment, the three-way interaction effects of investigated factors on tuber yield and attributes of tuber yield, the number of tubers more than 100 g, number of tubers between 50-100 g and number of tubers less than 50 g was significant. The interaction effects of planting date X salicylic acid foliar application and planting date X cultivar on plant height trait was significant, also the interaction effect of salicylic acid foliar application X cultivar was significant for the starch percentage trait and the simple effect of planting date and cultivar on the SPAD value trait was significant. In the following, the results of three-way interaction effects of the studied factors showed that the highest number of tubers more than 100 g in Sifra cultivar under 0.5 mM salicylic acid foliar application in 9 December planting date (with an average of 4.33 tubers per 1 kg), the highest number of tubers between 50-100 g related to the Challenger cultivar with 0.5 mM salicylic acid foliar spraying under 9 December planting date (with an average of 8.33 tubers per 1 kg), the highest number of tubers less than 50 g related to the Challenger cultivar under 26 December planting date and non-foliar application of salicylic acid (with an average of 33.33 tubers per 1 kg) and the highest tuber yield (with an average of 2.368 kg/m2) was related to the Sifra cultivar with 0.5 mM salicylic acid foliar application in the 9 December planting date. In addition, the highest amount of SPAD value belonged to the 25 November planting date (with an average of 42.61) and the Challenger cultivar (with an average of 42.41). Sifra cultivar also showed the highest starch percentage of tubers under 0.5 mM salicylic acid foliar application (with an average of 46.16%). Conclusion: Now, due to the lack of potato product in late winter, especially in the southern regions in the Iran, cultivation of early cultivars compatible with the region, such as Sifra on 9 December, in order to achieve optimal yield, and the use of salicylic acid foliar application is suggested in conditions similar to this study. [ABSTRACT FROM AUTHOR]

Like other high-latitude seas, the subpolar Bering and Okhotsk Seas in the northernmost Pacific Ocean changed rapidly from 1998 to 2018. The sea surface temperature (SST) increased by 0.62 and 0.41 °C/decade, respectively, much higher than the global rate of 0.108 °C/decade from 2000 until 2015. Despite this rapid warming, the chlorophyll content did not change significantly in the Bering Sea but increased by 0.047 μg/L/decade in the Okhotsk Sea. The Secchi disk depth (SDD) increased by 0.43 and 0.46 m/decade, respectively. Similar to other warm bodies of water, the SST of the subtropical/tropical South China Sea (SCS) also began rising, by 0.089 °C/decade, albeit more slowly than the global average. The chlorophyll content increased at 0.15 μg/L/decade from 1998 to 2006 but decreased by 0.11 μg/L/decade between 2007 and 2018. The SDD increased by 0.29 m/decade between 1998 and 2018. Although the SDD increased in all three seas, the chlorophyll concentration was maximum around 2006–2009, reflecting different phytoplankton responses to seawater warming. [ABSTRACT FROM AUTHOR]

The Soya Current is formed from the transformed subtropical waters of the Tsushima Current, which flows from the Sea of Japan through the La Perouse Strait, spreads along the northern coast of Hokkaido, and enters the Pacific Ocean through the Yekaterina and Kunashir straits. An analysis of satellite data (1993–2019) on sea level, geostrophic current velocity, surface water temperature, and chlorophyll concentration in the southern part of the Sea of Okhotsk, in the zone of the La Perouse Strait (Sea of Japan), and in the southern Kuril region of the Pacific Ocean has been carried out. It has been established that an increase in the sea level difference between the Sea of Japan and the Pacific Ocean leads to the intensification of the Soya current. The main contribution to the change in the level difference between the Pacific Ocean and the Sea of Japan in autumn belongs to anticyclonic eddies and meanders of the Subarctic Front in the Pacific Ocean. An increase (decrease) in the penetration of transformed subtropical waters through the La Perouse Strait is accompanied by an increase (decrease) in the temperature of the surface water layer in the southern part of the Sea of Okhotsk (r = 0.67 in 2000–2019) and a decrease (increase) in the chlorophyll concentration in the Kuril region of the Pacific Ocean (r = –0.70 in 1998–2019) in September–October. [ABSTRACT FROM AUTHOR]

In addition to nutrients and light, temperature plays a crucial role in marine biogeochemical processes. In this study, the sensitivity of the growth rate of phytoplankton to temperature was systematically studied by using a two-level nested physical–biogeochemical coupled model for the Yangtze River estuary of the East China Sea. The physical component of the coupled model is configured from the Regional Ocean Modeling System (ROMS) with the highest horizontal resolution of 3 km. The biogeochemical component of the coupled model is based on the carbon, silicon and nitrogen ecosystem model (CoSiNE). Five specific growth rate of phytoplankton equations with different relation to temperature were tested with the objective of reproducing the temporal evolution of chlorophyll concentration as observed by SeaWiFS. Our results indicate that the specific growth rate of phytoplankton equation which is from Geider's work, reaches a maximum at 22 °C and remains constant with higher temperature, can reproduce the seasonal variation of chlorophyll very well, and may be suitable for application in the physical–biogeochemical coupled model (ROMS-CoSiNE) of the Yangtze River estuary. [ABSTRACT FROM AUTHOR]

Summer blooms of potentially harmful cyanobacteria are common in the Baltic Sea. Under clear sky conditions, the cyanobacterial blooms are easily detectable from space. We propose a new regional algorithm for cyanobacteria biomass estimation from satellite data in the eastern part of the Gulf of Finland, developed on the basis of field measurements in July–August 2012–2014. The multi-regression equation defines the cyanobacteria biomass as a function of the particle backscattering coefficient and chlorophyll concentration. The use of this equation provides the best performance in comparison to the linear one, which is reflected in both R2 and RMSE values (0.61 and 272 mg m−3 respectively). Unlike other algorithms, which determine only the cyanobacteria bloom area in the Baltic Sea, our algorithm allows the determination of both a bloom area and its intensity. Considering the algorithm errors, the bloom detection threshold has been shifted from the 200 mg m−3 determined by biologists to 300 mg m−3. Based on data from the MODIS-Aqua satellite ocean color scanner, the spatial and temporal variability of cyanobacterial blooms in this region from 2003 to 2022 was analyzed. Significant interannual variability of cyanobacteria biomass was revealed in the central part of the studied region, with minimum values in 2014 and maximum in 2004. The record bloom during the studied period occurred in July 2004 (the average cyanobacteria biomass was 780 mg m−3). The weakest blooms were observed in 2009, 2010, and 2014, when both in July and August, the bloom areas did not exceed 30% of the study region.

The thin layers in the ocean are temporally-coherent aggregations of phytoplankton with high concentrations at small vertical scales, presenting important hotspots of ecological activity. Lidar could identify thin phytoplankton layers at a large spatial scale due to its capabilities of profile detection with a high efficiency. However, studies that linked thin layers to environmental factors are few, which limits our understanding of the layer formation mechanism. This paper investigates the characteristics and formation conditions of thin phytoplankton layers in the northern Gulf of Mexico using airborne lidar. The results depict that the chlorophyll concentration determines the formation probability of the phytoplankton layer. The layer is mainly formed at concentrations less than 6 mg m−3 and mostly distributed at 2 mg m−3. In addition, layer thicknesses were within 5 m and layer depths were mainly in the range of 10–15 m. Layer depths in the nearshore region were shallower than those in the offshore region. We conclude that the characteristics and formation conditions of the thin phytoplankton layers depend on the nutrients and light that are related to the seabed topography, turbidity, eddies and upwelling. The findings of this paper will enhance the understanding of layer formation mechanisms. [ABSTRACT FROM AUTHOR]

We present the performance of JAXA's SGLI standard algorithms for estimating chlorophyll a (chl a) concentration and the light absorption coefficients of colored dissolved organic matter (CDOM) using recently compiled high-quality data obtained from oceanic to coastal waters. Prior to the evaluation of the algorithms, we first compare two forward models (Gordon et al. in J Geophys Res 93(D9):10909-10924, 1988: G88 and Park and Ruddick in Appl Opt 44(7):1236–1249, 2005: PR05) using a wide range of inherent optical properties (IOPs) to (1) examine if the water reflectance is appropriately reproduced and (2) correct measured reflectance in terms of its bidirectionality. Based on a good reproducibility of water reflectance using the PR05, the optimized IOPs are further used for explaining errors in estimates of chl a concentration and CDOM absorption when using the SGLI, the GSM (Maritorena et al. in Appl Opt 41:2705–2714, 2002), and the QAA (Lee et al. in Appl Opt 41:5755, 2002) inversion algorithms. Results show that the mean error for estimating chl a concentration using the SGLI algorithm is 110% for our dataset. Although this error is lower than that of the GSM and the QAA algorithms, a significant underestimate at chl a higher than 2.0 mg m−3 is observed, which is further shown by independent match-up analyses. Another SGLI CDOM product includes the mean error of 50% and shows deviation at high CDOM range (> 1.0 m−1). A similar trend is observed for the GSM but not for the QAA when a global relationship of CDOM to colored detrital matter is applied. The sources of errors are discussed for potentially improving the retrievals. [ABSTRACT FROM AUTHOR]

More and more attention has been paid to the study of the impact of extreme climatic events on the ecological environment off the Changjiang River Estuary. In this study, the relationship between the chlorophyll concentration and ENSO (El Niño Southern Oscillation) events was studied. Several potential physical mechanisms between the ENSO and chlorophyll concentration were analyzed using observation and sensitivity experiments from a high-resolution ROMS-CoSiNE coupled model (Regional Ocean Modeling System-Carbon, Oxygen, Silicon, Nitrogen and Ecosystem) off the Changjiang River Estuary. Our results indicated that the April to August averaged chlorophyll concentration off the Changjiang River Estuary was significantly correlated with the December to February averaged ENSO indices in the previous winter. The 10 m wind speed and SST (Sea Surface Temperature) affected by an ENSO event had little effect on the chlorophyll concentration, while the discharge had a significant effect on the chlorophyll concentration off the Changjiang River Estuary, and the discharge was significantly and positively correlated with the ENSO indices. We tested the effect of interannual variations of the discharge and nutrients carried by discharge on the interannual variation in the chlorophyll concentration in the ENSO events. Two sensitivity experiments showed that when the nutrients in the freshwater discharge were kept as a constant seasonal cycle, the composite differences in the chlorophyll concentration between the positive and negative ENSO phases off the Changjiang River Estuary were reduced. When there were no nutrients in the freshwater discharge, the composite differences in the chlorophyll concentration between the positive and negative ENSO phases off the Changjiang River Estuary were reduced by one order of magnitude. The discharge can modify the stratification off the Changjiang River Estuary, and the nutrients carried by the discharge play a dominant role in determining the interannual variation of the chlorophyll concentration associated with the ENSO cycles.

The aim of this study was to evaluate some physiological parameters and biochemical changes in common bean plants (Phaseolus vulgaris) as a result of the foliar spraying of some nano stimulants (silicon, polyamine, seaweed and biofertilizer) under salt stress conditions. The pot experiment was conducted in the Agriculture Faculty's greenhouse at Menoufia University in Shibin El-Kom, Egypt during the two summer seasons of 2019 and 2020. Salt stress at level 6 dS/m significantly decreased growth, physiological characteristics, photosynthetic pigments, chemical measurements, and yield parameters. Meanwhile, the use of nano stimulators reduced the adverse effects of salinity by improving water relations, chlorophyll, enzymatic antioxidants (peroxidase and polyphenoloxidase), non-enzymatic antioxidants defense system (carotene, total soluble sugars, total amino acids, and proline), N, P and K and decreased Na+ concentrations resulted in high seed yield, particularly with nano silicon followed by nano biofertilizer. As the level of salinity increased, the seed weight (g/plant) decreased significantly by about 40% at the salt level 6 dS/m. In comparison to the control, using nano silicon resulted in significant increases in the leaf area, relative water content, proline concentration and seed weight by about 84, 53, 49 and 91%, respectively at 6 dS/m salinity level. To mitigate the negative impacts of salinity and improve the production, this study suggests spraying common bean plants with nano silicon followed by nano biofertilizer. [ABSTRACT FROM AUTHOR]

Some green orchids obtain carbon from both mycobionts and photosynthesis at the adult stage. Intriguingly, these orchids can produce albino and, in rare cases, variegated phenotypes. Here, we studied a Platanthera hondoensis population with green, variegated, and albino individuals. Although its closely related Platanthera species are usually associated with non-ectomycorrhizal rhizoctonias, and several studies have failed to find evidence of trophic plasticity in rhizoctonia-associated orchids, variegated and albino P. hondoensis must possess a higher fungal dependency than green P. hondoensis. Therefore, we investigated whether (i) P. hondoensis is associated with non-ectomycorrhizal rhizoctonias and (ii) the degree of mycoheterotrophy (using 13C abundance as a proxy) correlates with the foliar chlorophyll concentration. High-throughput DNA sequencing revealed that all P. hondoensis phenotypes were dominantly associated with a rhizoctonia from Ceratobasidiaceae belonging to a clade distinct from recognized ectomycorrhizal clades. Regression analysis revealed a positive linear relationship between foliar chlorophyll concentration and the degree of mycoheterotrophy. This study strongly suggests that rhizoctonia-associated P. hondoensis can dynamically adjust fungal exploitation in response to photosynthetic carbon levels. Since rhizoctonia is the most common orchid mycorrhizal partner, trophic plasticity may be a widespread adaptive trait in green orchids. [ABSTRACT FROM AUTHOR]

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• Four phenology-based bioregions characterise the eastern North Pacific coast. • Early spring blooms linked to positive SST anomalies and El Niño conditions. • Objective, unsupervised classification algorithm detecting blooms in all seasons. • 23-year Chl-a climatology provides average bioregion baseline of phenology. Phytoplankton phenology describes yearly algal growth cycles and characterises the timing, duration, and magnitude of bloom occurrences. This study used satellite chlorophyll-a data from 1998 to 2020 and the Hierarchical Agglomerative Clustering method to define phenoregions based on phytoplankton phenology spatial patterns over the British Columbia and Southeast Alaska coastal oceans. The defined phenoregions were used to simplify the spatial complexity of the heterogenous study region and thus better describe phytoplankton seasonality across the target area. The cluster analysis allowed the delineation of four coherent regions: two coastal regions and northern and southern shelf/offshore regions. Results showed that each phenoregion had distinguishable phytoplankton phenological characteristics, likely due to different physical forcings acting in these areas. Moreover, the interannual variability of the spring bloom initiation was evaluated considering interactions between sea surface temperature (SST) anomalies and the El Niño Southern Oscillation Index (ENSO). Early spring blooms were associated with positive SST anomalies and El Niño conditions; conversely, average or late spring blooms occurred in years with negative SST anomalies and La Niña conditions, with the strongest relationship occurring in the southern shelf/offshore phenoregion. This study provided new insights into the regionalisation of the British Columbia and Southeast Alaska coastal oceans based on phytoplankton phenology patterns. Given the critical role of phytoplankton as the base of the marine food web, such phenoregions have implications for regional zooplankton biomass and fish production. The link between phytoplankton phenology and climate drivers points to the importance of environmental change in phytoplankton bloom dynamics. Further research into the connection between phytoplankton bloom indices and zooplankton community structure and production would be an important step towards using these indices for ecosystem monitoring and fisheries management. [ABSTRACT FROM AUTHOR]

In studies of upwelling, usually data from infrared and optical sensors is used which provides information on the sea surface temperature (SST) and the chlorophyll-a (Chl-a) concentration. In this paper, we show that also synthetic aperture radars (SAR) images can give valuable contribution to such studies. Upwelling regions become detectable by SAR because they are associated with a reduction of the radar backscatter due to ① the change of the stability of the air-sea interface or/and ② the presence of biogenic slicks. Furthermore, the boundary of upwelling regions consists of a line of increased radar backscatter due to the presence of convergent surface flow.

• 3D RT simulations are used to assess the VI performance for estimating forest chlorophyll concentration. • Influences of saturation effect, soil backgrounds, and leaf area index disturbance on the chlorophyll concentration retrieval are evaluated. • Concern about decoupling vegetation canopy structure and spectral information. Remote-sensed vegetation indices (VIs) have emerged as essential tools for retrieving forest chlorophyll concentration. Although VIs are widely used, some concerns regarding VIs for estimating chlorophyll remain to be addressed, such as saturation effect, leaf area index (LAI) disturbance, and soil brightness influence. Currently, a systematic study on such performance evaluation of chlorophyll-related VIs considering these issues is still insufficient. This study coupled two radiative transfer models, the PROSPECT model and the LESS model, to simulate Eucalyptus monocultures with different chlorophyll content and systematically evaluated the 18 broad-band VIs' ability in chlorophyll estimation at different scales. Our results indicate that most VIs designed for chlorophyll estimation were relatively resistant to saturation, except for SIPI and some classical VIs (e.g., NDVI and DVI), which were insensitive to chlorophyll decreases and tended to reach saturation quickly (when leaf chlorophyll content (LCC) exceeded 40 ug/cm2). The relationships between NDVI, SR, DVI, and LCC were easily influenced by soil brightness and LAI. S2REP, MTCI, TGI, TCARI, and EVI were insensitive to soil brightness when estimating LCC. Overall, S2REP was best at quantitatively retrieving chlorophyll and resisting interference from other factors. For practical applications, our study suggests that it is preferable to use S2REP for LCC estimation when the red-edge band is available; otherwise, CVI can be used instead. The judicious utilization of VI can effectively depict chlorophyll levels and improve the understanding of vegetation response to climate change. Our findings provide the necessary information for the selection of specific VIs tailored to specific vegetation parameters. [ABSTRACT FROM AUTHOR]

Several strategies have been proposed recently to reduce the accumulated harmful circumstances of intensive conventional farming practices. The adoption of conservation soil tillage and organic fertilization techniques could contribute to achieving this goal. The study was conducted over a three-year trial to assess the effects of soil tillage practices (plough; subsoil; spading) and fertilization management (inorganic vs. organic) on durum wheat growth dynamics and productivity in a Mediterranean environment. The chlorophyll concentration (CC) was evaluated using an MC-100 chlorophyll meter, and Green Area (GA) was extracted from red-green-blue (RGB) digital images acquired with a commercially available digital camera. These non-destructive low-cost methods were used to examine crop status and its reactions to climate conditions over three consecutive growing seasons in the field. A positive strong linear relationship between both CC and GA against grain yield in each growing season was identified. The study highlights that CC and GA methods are valuable tools to assess crop development under Mediterranean conditions. The results indicated that the applied conservation tillage systems, such as subsoil tillage and using the spading machine, along with organic fertilization with compost, are valuable choices in the Mediterranean basin for sustainable and higher crop production (13%) compared to the conventional traditional system.

The aim of the present study was to evaluate the effect of different levels of mineral nutrient availability on development and physiological performance of several common indoor ornamental plant species (Anthurium sp., Chlorophytum comosum, Epipremnum aureum, Plectranthus fruticosus, Spathiphyllum sp., and Tradescantia pallida) cultivated in hydroponics with potential use in active botanical biofilter systems. Plants were grown in expanded clay granules at four levels of mineral nutrient availability provided by two types of commercial mineral fertiliser. The growth stimulative effect of increased mineral nutrient availability depended on plant growth rate, with a lower effect on slower growing species. The need for nutrients increased in the order Anthurium < Spathiphyllum < Epipremnum < Chlorophytum < Tradescantia < Plectranthus. Tissue water content showed pronounced differences between various plant species as well as between plant organs. For several species, increase in mineral nutrient availability resulted in a significant increase in tissue water content. Chlorophyll fluorescence analysis showed that indoor plants can successfully adapt to low and moderate mineral fertiliser levels with balanced individual nutrient rates, without negative consequences to photochemistry of photosynthesis. Consequently, indoor plants can be cultivated at a relatively low concentration of mineral nutrients for optimum utilisation in active botanical biofilter systems. [ABSTRACT FROM AUTHOR]

The article presents data of the beam attenuation coefficient, Secchi disk depth, and chlorophyll concentration in a survey area in the northern tropical zone of the Atlantic Ocean in summer 1986. The relationship between the bio-optical characteristics and water dynamics is considered. The chlorophyll concentrations in summer 1986 are compared with those observed in autumn 2002. [ABSTRACT FROM AUTHOR]

The objective of this work was to characterize the spatiotemporal variability in satellite-derived chlorophyll concentration (Chlsat), primary productivity (PP), sea surface temperature (SST), and sea surface height (SSH) in the Campeche Bank from July 2002 to December 2018. Monthly composites of Chlsat and SST (MODIS-Aqua sensor) and SSH (COPERNICUS) were downloaded. PP compositions were downloaded from the Oregon State University web page. Four transects running perpendicular (T1 to T4) and 1 parallel (T5) to the coast of Campeche were studied. Time series and Hovmöller diagrams were constructed to study the spatial and temporal variations. The Chlsat in T1 to T4 showed a clear separation between an inner zone (0-60 km) and an outer zone (60-200 km). The inner neritic zone showed maximum Chlsat (>2.5 mg·m-3) and PP (>2 g C·m-2·d-1) values in the rainy season and minimum values in the dry season (<2 mg·m-3 and <2 g C·m-2·d-1, respectively) because freshwater input in the inner zone provides nutrients for phytoplankton growth. The outer neritic zone showed the highest Chlsat (>0.6 mg·m-3) and PP (>0.7 g C·m-2·d-1) values during cold fronts and the lowest during the dry season (<0.3 mg·m-3 and <0.4 g C·m-2·d-1) because cold fronts mix the water column and thus carry nutrients into the euphotic zone. SST showed maximum values (>30 °C) during the rainy season and minimum values (<22 °C) during cold fronts; maximum SSH (>0.40 m) occurred during cold fronts, and minimum SSH (<0.25 m) occurred during the dry season. [ABSTRACT FROM AUTHOR]

Selection in the absence of competition under ultra-low density has been proposed as a mean to develop new cultivars serving the needs of a sustainable agriculture under diverse climatic conditions. In 2018, individual high-yielding plants of the determinate type bean varieties (Phaseolus vulgaris L.) Iro and Pirgetos were selected in R21 honeycomb design trials under normal and deficit irrigation treatments. This led to 14 high-yielding second generation lines from cultivar Iro and four from cultivar Pirgetos which together with the original varieties were evaluated again in 2019 under the same ultra-low density and irrigation conditions. Water stress affected total chlorophyll content measured in selected individual plants from start of flowering until physiological maturity with some of the second generation lines showing similar or higher chlorophyll concentrations from the original varieties especially during the seed filling stage. Significant differences between normal and deficit irrigation were also shown on CO2 assimilation rate for all genotypes, but there were no significant differences between the evaluated progenies and their respective ancestors. Compared to the original variety Iro, four of the second generation lines had similar or higher yield plant-1 (up to 15%) and exhibited the highest stability under both normal and water deficit conditions, whereas for the variety Pirgetos two progenies outperformed the original cultivar (by 5,5 to 27%). Further research is under way for a final evaluation of the selected progenies under farming density and water stress. [ABSTRACT FROM AUTHOR]

As part of a recent MArch Landscape Urbanism thesis project at the Architectural Association (AA) in London, Daniel Kiss and Swadheet Chaturvedi investigated the food chains that impinge on Antarctica, which are deeply intertwined with the health of our planet. The authors zero in, for example, on the fishing of krill, illustrating its domains and positing dynamic protections for sustainable modes of harvesting. [ABSTRACT FROM AUTHOR]

Abstract Objectives A field experiment was conducted to evaluate Soil Plant Analysis Development (SPAD) value in different age and leaf of maize hybrid and correlating with grain yield. Ten maize hybrids were replicated thricely under Randomized Complete Block Design (RCBD) during winter of 2018. SPAD value was measured by SPAD 502 plus meter. At 30 days interval during vegetative stage SPAD measurement were taken from T1 (top most leaf) and T3 (2nd leaf from top leaf) leaves of five randomly selected plants from one plot and they were averaged. For reproductive phase data taken from eo (leaf attached to ear) and e2 (2nd leaf from eo leaf) leaves at 10 days intervals. Same leaves were used for entire data collection. Results Significantly different SPAD value was observed for different age and leaves of maize during pre and post anthesis. SPAD value increase with increase in age and decrease at the time of maturity. During vegetative phase T3 leaves has more SPAD value than T1. During reproductive stage eo leaves had more SPAD than e2 leaves, so center leaf of maize contributes more to grain yield. Correlation showed that there is strong positive correlation between different stage of SPAD with grain yield.

We propose this fluorescent express method for the assessment of the chlorophyll a concentration in seawater. The method is based on spectral fluorescence measurements obtained with excitation at different wavelengths. A relatively simple two-channel laser spectrometer is used for measurements. In this case, preliminary preparation of samples is not required. We estimated the errors of the method by comparison with the results of direct measurements of the chlorophyll a concentration. A large array of measurement data obtained in the seas of the North Atlantic and the Arctic was used for the analysis. The possibility of reducing errors in the transition from one-dimensional regression to multidimensional is shown. It has also been shown that the accuracy of the assessment is comparable to the fluorescent extraction methods for determining the chlorophyll a concentration: errors of 40–50% when using the general formula and 20–35% after post-cruise calibration.

Like other high-latitude seas, the subpolar Bering and Okhotsk Seas in the northernmost Pacific Ocean changed rapidly from 1998 to 2018. The sea surface temperature (SST) increased by 0.62 and 0.41 °C/decade, respectively, much higher than the global rate of 0.108 °C/decade from 2000 until 2015. Despite this rapid warming, the chlorophyll content did not change significantly in the Bering Sea but increased by 0.047 μg/L/decade in the Okhotsk Sea. The Secchi disk depth (SDD) increased by 0.43 and 0.46 m/decade, respectively. Similar to other warm bodies of water, the SST of the subtropical/tropical South China Sea (SCS) also began rising, by 0.089 °C/decade, albeit more slowly than the global average. The chlorophyll content increased at 0.15 μg/L/decade from 1998 to 2006 but decreased by 0.11 μg/L/decade between 2007 and 2018. The SDD increased by 0.29 m/decade between 1998 and 2018. Although the SDD increased in all three seas, the chlorophyll concentration was maximum around 2006–2009, reflecting different phytoplankton responses to seawater warming.

The riparian areas of the lake Mikri Prespa in the northwest of Greece are surrounded by extensive reedbeds (mainly Phragmites australis and Typha angustifolia reed) that spread around the perimeter of the lake. The removal of this vegetation is often problematic and imposes difficulties in management and costs. The goal of the present study was to evaluate the effect of the direct use of reed biomass on soil fertility and the performance of common bean (Phaseolus vulgaris L.) type "Plake", the main crop in the Prespa region. In a two year field experimentation we tested two fertilization methods, manure and chemical fertilization, combined with three reed biomass doses (0 as a control, 10 tn ha-1 and 20 tn ha-1) resulting in five different reed addition treatments (0-0, 10-10, 10-0, 20-20 and 20-0 for the two consecutive years and each fertilization method respectively). Total chlorophyll content measured from start of flowering until physiological maturity was not affected by the incorporation of reed biomass in both fertilization methods. The chemical fertilization significantly affected bean yield exceeding the application of manure in all treatments of reed plant material addition. Reed plant addition treatments affected bean yield with all treatments showing higher values compared to the control (0-0) while the addition of 20 tn ha-1 for one year (20-0) significantly exceeded the control regardless of the fertilization method. Further research is needed to explore the best agricultural practice on the effect of reed addition on arable land improvement and the bean crop. [ABSTRACT FROM AUTHOR]

This work compares the tolerance to long-term anoxia conditions (35 days) of five new citrus ‘King’ mandarin (Citrus nobilis L. Lour) × Poncirus trifoliata ((L.) Raf.) hybrids (named 0501XX) and Carrizo citrange (CC, Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), the widely used citrus rootstock in Spain. Growth parameters, chlorophyll concentration, gas exchange and fluorescence parameters, water relations in leaves, abscisic acid (ABA) concentration, and PIP1 and PIP2 gene expressions were assessed. With a waterlogging treatment, the root system biomass of most hybrids went down, and the chlorophyll a and b concentrations substantially dropped. The net CO2 assimilation rates (An) and stomatal conductance (gs) lowered significantly due to flooding, and the transpiration rate (E) closely paralleled the changes in gs. The leaf water and osmotic potentials significantly increased in most 0501 hybrids. As a trend, flooding stress lowered the ABA concentration in roots from most hybrids, but increased in the leaves of CC, 05019 and 050110. Under the control treatment (Ct) conditions, most 0501 hybrids showed higher PIP1 and PIP2 expressions than the control rootstock CC, but were impaired due to the flooding conditions in 05019 and 050110. From this study, we conclude that 0501 genotypes develop some adaptive responses in plants against flooding stress such as (1) stomata closure to prevent water loss likely mediated by ABA levels, and (2) enhanced water and osmotic potentials and the downregulation of those genes regulating aquaporin channels to maintain water relations in plants. Although these traits seemed especially relevant in hybrids 050110 and 050125, further experiments must be done to determine their behavior under field conditions, particularly their influence on commercial varieties and their suitability as flooding-tolerant hybrids for replacing CC, one of the main genotypes that is widely used as a citrus rootstock in Spain, under these conditions. [ABSTRACT FROM AUTHOR]

In addition to nutrients and light, temperature plays a crucial role in marine biogeochemical processes. In this study, the sensitivity of the growth rate of phytoplankton to temperature was systematically studied by using a two-level nested physical–biogeochemical coupled model for the Yangtze River estuary of the East China Sea. The physical component of the coupled model is configured from the Regional Ocean Modeling System (ROMS) with the highest horizontal resolution of 3 km. The biogeochemical component of the coupled model is based on the carbon, silicon and nitrogen ecosystem model (CoSiNE). Five specific growth rate of phytoplankton equations with different relation to temperature were tested with the objective of reproducing the temporal evolution of chlorophyll concentration as observed by SeaWiFS. Our results indicate that the specific growth rate of phytoplankton equation which is from Geider’s work, reaches a maximum at 22 °C and remains constant with higher temperature, can reproduce the seasonal variation of chlorophyll very well, and may be suitable for application in the physical–biogeochemical coupled model (ROMS-CoSiNE) of the Yangtze River estuary.

The thin layers in the ocean are temporally-coherent aggregations of phytoplankton with high concentrations at small vertical scales, presenting important hotspots of ecological activity. Lidar could identify thin phytoplankton layers at a large spatial scale due to its capabilities of profile detection with a high efficiency. However, studies that linked thin layers to environmental factors are few, which limits our understanding of the layer formation mechanism. This paper investigates the characteristics and formation conditions of thin phytoplankton layers in the northern Gulf of Mexico using airborne lidar. The results depict that the chlorophyll concentration determines the formation probability of the phytoplankton layer. The layer is mainly formed at concentrations less than 6 mg m−3 and mostly distributed at 2 mg m−3. In addition, layer thicknesses were within 5 m and layer depths were mainly in the range of 10–15 m. Layer depths in the nearshore region were shallower than those in the offshore region. We conclude that the characteristics and formation conditions of the thin phytoplankton layers depend on the nutrients and light that are related to the seabed topography, turbidity, eddies and upwelling. The findings of this paper will enhance the understanding of layer formation mechanisms.

In order to evaluate the effects of NaCl stress on seedlings of Salix matsudana Koidz, the effects of different NaCl concentrations (0, 0.1 %, 0.2%, 0.4%) on one-month-old S. matsudana seedlings grown Ill an envrronment- controlled chamber for 28 days was examined. Responses of S. matsudana were monitored in relation to physiological parameters, leaf fall ratio, relative water content (RWC), photosynthetic gas exchange characteristics and chlorophyll fluorescence parameters and chlorophyll concentration. The plants did not show any effect on survival and grew normally without toxic symptoms under 0.1% NaCl, and had different numbers of yellow leaves at the base of the seedlings and new leaves dried under 0.2% and 0.4% NaCl for 28 days. Plant growth, biomass and RWC decreased linearly with an increase in salinity and duration. After the experiment, over a half of the leaves that were treated with 0.4% NaCl had fallen. The chlorophyll contents in the leaves decreased with increasing of NaCl salinity. Leaf photosynthetic gas exchange parameters (net photosynthetic rate, transpiration rate, intercellular CO2 concentration and stomata! conductance) showed varying correlations and an overall decrease in these parameters under NaCl treatment period compared with the control. The decrease tendency in photochemical efficiency of PSII (Fv'/Fm'), actual photochemical efficiency of PSII (