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IntroductionIn recent decades, the introduction of high-yielding cultivars under optimal conditions has been the main focus of grain research programs. The identification of wheat cultivars that have acceptable yields on different planting dates has been taken into account.Materials and MethodsThe present split-plot test was performed with three replications in two cropping years, 2016-2017 and 2017-2018. The main factor included three planting dates (October 20, November 20, and December 20 as early, normal, and delayed planting dates), and the sub-factor included six wheat cultivars (Zare with winter growth habits, Heidari, Pishgam, and Alvand with facultative growth habits, and Sirvan and Pishtaz with spring growth habits). The soil was sampled from a depth of 0 to 30 cm before the experiment, and the physical and chemical traits of the soil were determined. Land preparation steps were performed before the experiment. For this purpose, a land area of 1500 m2 was plowed by a reversible plow and then leveled. Fertilizer application was performed based on the soil experiment results as 100 kg.ha-1 of triple superphosphate, 100 kg.ha-1 of potassium sulfate, and 100 kg.ha-1 of urea before planting. The rest of the urea fertilizer (200 kg.ha-1) was applied at the stage of stem emergence and the beginning of anthesis wheat. Iron, zinc, and manganese fertilizers were also used from their sulfate sources at the rate of 0.2%, which were sprayed in two stages at the beginning of stalking and spiking. Each plot was 5 m long and 2 m wide and consisted of 8 planting rows at a distance of 25 cm. A distance of 50 cm was considered between the two sub-plots and 1 m between the two main plots. The required seed for each experimental plot was determined and distributed based on the density of 400 seeds per m2 based on the weight of 1000 seeds of each cultivar. Irrigation was performed immediately after planting. Agricultural care was applied uniformly, including pest, disease, and weed control. In each subplot, 50 cm from the beginning and end of the rows was considered as the margin. All data were subjected to ANOVA using the GLM procedure of SAS (SAS 9.1) and means were compared by using the Duncan test at 5% probability level.Results and DiscussionThe results showed that delayed planting reduced nutrient uptake and increased the extinction coefficient. Radiation use efficiency on the planting date of December 20 showed a reduction of 27% and 25%, compared to the planting date of October 20 in 2016-2017 and 2017-2018, respectively. Also, on December 20, Sirvan and Pishtaz cultivars with spring growth habits showed lower extinction coefficients and higher photosynthesis rates than winter and facultative cultivars. On October 20 and November 20, the highest grain yield was obtained in cultivars with winter and facultative growth habits. On December 20, the grain yield was higher in cultivars with facultative and spring growth habits than in winter cultivars. Late planting of wheat cultivars with winter growth type, which must receive low temperatures for Vernalization, is very risky. Because delaying planting may lead to a sharp decrease in yield. These negative consequences of the delay in planting may have occurred through disruption of absorption of water, nutrients, and absorption of active photosynthetic radiation. Late cultivation shortens the vegetative growth period and the plant enters the reproductive stage prematurely, and then the plant faces a lack of photosynthetic resources. Also, the grain filling period is faced with drought and heat stress at the end of the season and this final stress causes a sharp decrease in yield.ConclusionIn general, the delayed planting significantly reduced grain yield, especially in cultivars with winter growth habits. Therefore, it is recommended to use intermediate and spring cultivars for delayed cultivation.

In order to investigate the effect of wood vinegar and humic acid on morphological and biochemical traits, antioxidant enzymes, and peppermint essential oil under water deficit stress conditions, an experiment was conducted as split plot based on randomized complete block design with three replications in the research farm of the Faculty of Agriculture of the Tarbiat Modares University. The experimental treatments were irrigation regimes at three levels (irrigation up to the field capacity and after depletion 25 (optimal irrigation), 40 (moderate water deficit stress), and 55 (severe water deficit stress) % of plant available water in the root zone, respectively) as main plots and foliar application at seven levels (humic acid (1, 2, and 3%), wood vinegar (5, 10, and 15%) and no foliar application (control)) as sub plots. The highest plant height (38.63 cm) was obtained from the treatment of using wood vinegar 15% under optimal irrigation conditions, while, the maximum leaf area index (3.01) was observed in the treatment using wood vinegar 15% under moderate water deficit stress conditions. The maximum essential oil yield was observed in the foliar application of humic acid 3% under optimal irrigation conditions with 37.48 kg h-1, and with the treatments of humic acid 2% under optimal irrigation conditions with 34.34 kg ha-1 and foliar application of 15% of wood vinegar under optimal irrigation conditions with 36.11 kg ha-1 was placed in a statistical group. An increase in water deficit stress caused a decrease in essential oil yield, so that in moderate and severe water deficit stress, 9.37% and 40.17% of essential oil yield decreased, respectively. The use of wood vinegar and humic acid increased the yield of peppermint essential oil, so that by increasing the foliar concentration of wood vinegar from 0 to 15%, the yield of essential oil increased by 81.29%, and increasing the concentration of humic acid foliar application from 0 to 3% increased the yield of essential oil by 69.28%. Considering the water limitation, the use of acid humic 3% is recommended in optimal irrigation conditions and moderate water deficit stress, and wood vinegar 15% in severe water deficit stress conditions is recommended. [ABSTRACT FROM AUTHOR]

IntroductionCamelina [Camelina sativa (L.) Crantz] oilseed is a low-input crop that grows and yields well in semiarid regions with low-fertility or saline soils in comparison with other crops. Camelina seeds contain 30–40 percent oil. Camelina is an annual plant from the Brassicaceae family that has short and fast growth. Camelina is well adapted to cool temperate and semi-arid climates, it is more tolerant of drought and spring freezing than rapeseed (Brassica napus L.). Also, Resistance to some diseases and pests of other members of Brassicaceae plants is another important features of this plant. Research-based information is lacking to provide basic agronomic recommendations for Camelina. In general, yield and yield components of Camelina seeds depends on nitrogen fertilization, planting time and climatic conditions. Camelina responds differently to fertilizer management and planting date in different climatic and soil conditions. Selection of crop managements such as planting date and fertilization can increase the quantitative and the qualitative yield of this plant.Materials and MethodsIn order to evaluate the effects of nitrogen fertilizer on agronomic characteristics in Camelina under different planting dates, a study was conducted in split-plot based on randomized complete blocks design with three replications at the research field of Agricultural College, the Shahid Chamran University of Ahvaz, located in the southwest of Ahvaz and the western bank of the Karun River with 31°19׳ʹ N; 48° 41׳ʹ an altitude of 22 meters above sea level during 2018-19 growth season. Experimental factors included planting date in three times (November 6, December 6 and January 5) as the main plots and nitrogen fertilizer at four levels (0, 23, 46 and 69 kg.ha-1) as the subplots. The plant material (seed) of this research was Camelina sativa cultivar Soheil which was prepared from the Biston Shafa Knowledge Foundation Company. Half of the nitrogen fertilizer was spread with phosphorus and potassium in the surface of each experimental unit and mixed with soil before planting. The other half of nitrogen fertilizer used in three sections during three stages of plant phenology included True four leaves, beginning of stem elongation and beginning of silicle emergence.Results and DiscussionAnalysis of variance of traits showed a significant difference between nitrogen levels at each level of planting date in terms of all traits studied, including grain yield, biological yield, harvest index, plant height, percentage and oil yield, etc. Generally, based on the results of the analysis of variance, in all three planting dates. The highest grain yield (2653.8 kg.ha-1) was obtained from the first planting date and 46 kgN.ha-1 treatment and the highest harvest index in second planting date and 46 kg nitrogen treatment was measured. The highest oil yield (737.9 kg.ha-1) belonged to the first planting date and the level of 23 kgN.ha-1. However, the highest protein percentages (28.53) was obtained in the second planting date and 69 kg nitrogen treatment. Regarding to the other traits, it was observed that the optimal use of nitrogen fertilizer led to the improvement of the studied traits such as the number of sub-branches, silicle per plant, seed per silicle and 1000-grain weight, but delay in planting date caused the mean of these traits decreased significantly.ConclusionIn general, the results of this study showed a significant response of Camelina to the amount of nitrogen used and planting date, so that in early planting (November 6) was obtained the highest grain yield, yield components, biological yield, oil yield and protein percentage. But in late planting, especially the third planting date, all the studied traits were reduced due to the collision of the plant reproductive stage with the high temperature at the end of Khuzestan growth season and the reduction of the plant growth cycle. Under three planting dates, nitrogen fertilizer application up to 46 kgN.ha-1 increased grain yield, oil yield and some yield components. Based on the results of this experiment, in order to obtain maximum grain and oil yield of Camelina, it is important to consider planting date and optimum nitrogen use.

The current study was aimed at determining the optimum time of urea foliar spray to improve fruit quantity and quality (fruit set%, yield, size, peel thickness of fruits, titrable acidity (TA), total soluble solid (TSS)) of 'Thomson Navel' orange trees (Citrus sinensis L. Osbeck.) for 2 consecutive years. Thus, a 0.5% solution of urea was sprayed on to 20 years old orange trees during January (T1), March (T2) and June (T3). There was a set of control trees that only sprayed with simple water (T0). The results showed that the trees receiving foliar applied urea, independent of application time, had significantly greater leaf nitrogen content and fruit set % than the control trees. In addition, the impact of the urea foliar application on the yield and quality properties of fruits was significant (P<0.05). The effect of urea spray time on TSS/TA (maturity index) and yield depended on studied year. In first year (low yield), the highest level of yield observed in T1 and T3 treatments and the highest level of TSS/TA observed in T0 treatment. In second year (high yield), the highest level of yield and TSS/TA observed in T2 and T3 treatments. Therefore, it is important to determine the optimal level and time of application of nutrients to stimulate a specific physiological process in citrus, depending on the studied year (high yield or low yield). [ABSTRACT FROM AUTHOR]