Study of some Morphophysiological Characteristics of Several Rapeseed Cultivars Using Vermicompost Fertilizer in Drought Tension Conditions

Water deficiency is one of the most important factors limiting canola production in arid and semi-arid regions in Iran. In order to investigate the effect of drought tension through irrigation cut at the end of the season and application of vermicompost on some morphophysiological characteristics of rapeseed, a factorial-split experiment in the form of a randomized complete blocks design with three replications was carried out at Karaj Seed and Plant Improvement Research Institute in 2015 and 2016. Experimental factors include irrigation regime at three levels (full irrigation during the season, irrigation cut from the podding stage to the end of the season and irrigation cut from the flowering stage to the end of the season) and vermicompost at two levels (non-application and application of 20 tons per hectare) as the factorial in the main plot and genotype at 6 levels (RGS003, Zafar, Julius, Jerry, Zabol10 and Hyola4815) in the subplots. The results of analysis of variance showed that the effect of year, irrigation, vermicompost and cultivar on the measured traits was significant at the level of 1 percent probability. Mean comparison showed that the plants in the second year had higher height, stem diameter, number of pods and chlorophyll content than the first year, but the amount of soluble carbohydrates, stomata resistance and canopy temperature of the plant in the first year was higher than the second year. The highest height, number of pods, leaf chlorophyll and stem diameter belonged to Zafar cultivar under normal irrigation conditions and the lowest value was observed in Zabol10 cultivar under irrigation cut conditions from flowering stage. Plant height, number of pods, stomatal resistance and canola leaf chlorophyll in vermicompost application conditions were higher than non-vermicompost application conditions, but the values of soluble carbohydrates and canopy temperature were higher in vermicompost application conditions. The highest amount of soluble carbohydrates in leaves belonged to Zabol10 cultivar in the conditions of irrigation cut from flowering stage and the lowest amount of soluble carbohydrates in Zafar cultivar was observed in normal irrigation conditions. The highest stomatal resistance belonged to Zafar cultivars in irrigation cut-off treatment at flowering stage and the lowest in Zabol10 cultivar in normal irrigation conditions. The lowest and highest canopy temperatures were observed in normal irrigation conditions and irrigation cut from flowering stage, respectively.