The effect of drought stress and zeolite application on physiological traits, and anti-oxidant enzymes activity, and qualitative and quantitative performance of rapeseed (Brassica napus L.) genotypes

In order to study the effect of zeolite on some physiological characteristics, antioxidant enzymes activity, seed and oil yields of rapeseed (Brassica napus L.) under drought stress condition, a split plot factorial experiment was conducted based on a randomized complete block design with four replications in Seed and Plant Improvement Institute in Karaj. Three drought stress levels (irrigation after 40, 60, and 80% soil water discharge), were applied as non-stress, low stress, and high stress, respectively and the zeolite at two levels (0 and 10 tons per hecater) was applied in a factorial design in main plots while genotypes of rapeseed (Line KR4 and Eldo and GKH 305 and Anatol cultivars) were used in sub-plots. Results revealed that in all zeolite and rapeseed genotype treatments, drought stress caused a decrease in relative water content, canopy temperature, and stomatal resistant and decreased soluble sugar, proline content, and antioxidants activity (catalase and peroxidase) and malondealdehyde in top young leaves in plant. The moderate and severe drought stress led to reduction in seed yield and oil yield, respectively. With an increase in stress level, so did the efficiency of zeolite in reducing negative effects of stress and its application under moderate and high stress resulted in significant reductions in catalase and peroxidase antioxidant activities and also reduction in soluble sugars and proline concentration. Application of zeolite increased seed yield significantly under non-stress, moderate and high stress treatments and improved oil yield. Among genotypes under study, KR4 line and GKH305 cultivar had the highest seed yield in case of application and non-application of zeolite, respectively but under moderate and severe stress, Anatol had the lowest loss and highest yield. According to the findings, using zeolite in all drought stress caused a significant decrease in rapeseed yield and with an increase in water limitation, so did the efficiency of zeolite.