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In order to study the effect of limited-irrigation stress on canola cultivars, an experiment was conducted in 2007-2008 at the Safiabad agricultural research center. The design was a split plot in a completely randomized block basis with three replications. Main plots were consisted of 4 levels of limited-irrigation, irrigation based on 60 mm cumulative evaporation (Control), withholding irrigation in flowering stage, withholding irrigation in pod initiation and irrigation withholding in grain filling period, and subplots were 5 canola cultivars (Hyola308, Hyola330, Hyola401, Hyola420 and RGS003). The mean comparison of interaction showed that the highest (3155.55 kg.ha-1) grain yield appointed to Hyola420 cultivar in optimum irrigation (control treatment), and the lowest (1491.66 kg.ha-1) belonged to RGS003 cultivar at withholding irrigation in pod initiation period. The maximum (161.42) number of pods observed on Hyola330 cultivar at optimum irrigation (irrigation after 60 mm cumulative evaporation), and the minimum (78.1) ones appointed to RGS003 cultivar at withholding irrigation in pod initiation period. Results showed that there was no significant difference among withholding irrigation, cultivars and the interaction effect of them for oil content. By considering the results of this experiment, withholding irrigation at flowering, pod initiation and grain filling periods leads to decrease grain yield by 24.72%, 14.33% and 11%, respectively. Reduction of grain yield due to the withholding irrigation during flowering, podding and grain filling stages was along with a decrease in the number of pods per plant and thousand seed weight. By considering the results of experiment, withholding irrigation in flowering stage has to be avoided.

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Studyign of soybean cultivars under abiotic stress conditions to improve their yield is important. This experiment was carried out as a strip plot based on a randomized complete block design with three replications in the Safiabad Argicultural Research Center. Vertical factor consisted of foure levels of irrigation (Irrigation after 50, 90, 130 and 170 mm evaporation from class A pan) and horizontal factor was 6 soybean genotypes (504, Katoul, Safiabadi, BP×Safiabadi, Migmat and Salend). Results showed that the effect of drought stress, genotypes and their interactions were significant on grain yield. The mean comparison of drought stress × genotype interaction showed that the highest grain yield (4522 Kg ha-1) achieved in irrigation after 50 mm evaporation from class A pan in Migmat and the lowest grain yield (1017 Kg ha-1) belonged to Katoul genotype with irrigation after 170 mm evaporation from class A pan. Pod number per plant decreased by 16%, 28% and 51% with increasing irrigation intervals to 90, 130 and 170 mm compared to irrigation after 50 mm evaporation. The treatments did not have any significant effect on the number of grain per pod. It is concluded that, irrigation after 50 mm evaporation from class A pan would be suitable for Migmat and BP×Safiabadi genotypes. Irrigation after 90 mm evaporation from class A pan appropriate for 504, Salend, Katoul and Safiabadi genotypes.

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In order to investigate the effects of boron, zinc and sulfur on quantitative and qualitative characteristics of rapeseed (Hyola 401 cultivar), an experiment was conducted at Rice Research Institute of Iran, Rasht province in 2011. A field experiment with completely randomized block design was performed with eight treatments in three replications. Treatments consisted of control, zinc was added as Zn 15% EDTA at the rate of 1.5 kg ha^−1 were applied to the soil, Boron was added as Borax at the rate of 1.5 kg ha^−1, sulfur treatment added at the rate 100 kg ha^-1 before of sowing, B+Zn, B+S, Zn+S and B+Zn+S. Maximum grain yield (4157.6 kg ha^-1) was obtained from S+B+Zn treatments that increased the seed yield by 48.7% compared to the control. Maximum and minimum oil content obtained from B+Zn+S (42.58%) and control (38.37%). Maximum protein (24.62%) was obtained from zinc fertilizer. The highest leaf boron, zinc and sulfur content were obtained in treatments B+Zn+S of 15.7, 26.38 and 577.4 mg kg^-1 respectively, and minimum nutrients content was obtained in control. Regards to the experiment results, the application of B+S fertilizer increased the seed yield and oil content and is suggested in Rasht reign conditions.

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In order to determine the appropriate sowing dates, seed rates and their interaction effects on yield and yield components, oil and protein contents of soybean variety Sari, a split-plot experiment based on a randomized complete blocks design with four replications was carried out at Qaemshahr Gharakeil Agriculture Research Station in 2009. Five sowing dates including 15^th May, 31^th May, 15^th June, 1^th July and 16^th July were considered as main plots and three different seed rates including 60, 75 and 90 kg ha^-1 as the sub-plots. The results showed that all of yield components were affected by sowing dates and also seed rates had a significant effect on the number of pods per plant. Although due to increasing seed rates, yield components, such as pods per plant were decreased, but because of the increasing number of plants per square meters, seed yield not decreased significantly. Therefore for economically saving 60 kg ha^-1 of seed rates will be preferred. In this study high mean value of seed yield, biological yield and 1000-seed weight was achieved in first sowing date and all of the yield component characters were decreased in late sowing dates. Harvest index was increased in late sowing dates and it was not significantly affected by seed rates. Sowing dates and seed rates had not significant effects on oil and protein percentages, but due to significant effects of sowing dates on seed yield, oil and protein yields were significantly affected by sowing dates. In this study higher seed yield was belonged 60 kg ha^-1 of seed rate in first and second sowing dates which have not significant statistically differed.

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A field experiment was carried out to study the yield, quality and some morphological traits responses of spring canola (Brassica napus L.) to boron application and sowing date, in Ramin Agriculture and Natural Resources University of Khuzestan in 2013-2014. The experiment was carried out as a split plots design in basis of RCBD with three replications. Planting dates (18 November, 3 December, 17 December and 30 December) and boron application treatments (control, 10 kg B.ha^-1 incorporated with soil, boron spraying at 6 leaf stage and budding stages) were investigated as main and sub plots, respectively. Planting dates and boron application had significant effects on morphological traits, yield and quality of canola. The interaction effect of sowing date and boron on grain number per siliquie was significant. Late planting caused to significant decreased yield and its components. However, boron application incorporated with soil caused to compensate the negative effect of late planting. Generally, the highest grain yield (4579.7 kg.ha^-1) was obtained from sowing at 18 November and 10 kg boron.ha^-1 incorporated with soil, and lowest grain yield was obtained from planting at 30 December and without boron application. Delayed planting result in lowering morphological traits including plant height and branching. Delayed planting also caused by decreased grain oil and leaf N percentage, and increased grain N percentage. Boron application caused by significant plant boron content, but had no significant on grain oil ad N, and leaf N content. Also, boron application, in the experiment had no significant effect on alleviation of yield loss due to delayed canola sowing.