Comparison of antioxidant enzymes and proline roles in drought tolerance of rapeseed (Brassica napus L.)

In order to comparison of antioxidant enzymes and proline roles in drought tolerance of rapeseed, an experiment was conducted at the research field of Yazd Agricultural and Natural Resources Research Center in 2011-2012. In this study, three commercial rapeseed genotypes (GKH2005, Opera and Okapi) were examined for response to irrigation treatments such as nonstress conditions (control) and withholding irrigation from stem elongation, flowering and silique formation stages in four separate experiments based on randomized complete block (RCB) design. The results indicated that proline accumulation, activity of catalase and proxidase enzyme and lipid peroxidation index (content of malondealdehyde) were higher in drought stress treatments, but these amounts were different in three rapeseed genotypes. Maximum activity of antioxidant enzymes and low content of malondealdehyde was observed in GKH2005 compared with others, in drought stress conditions. Between these genotypes, GKH2005 produced the highest seed yield under non-stress conditions and withholding irrigation from stem elongation, flowering and silique formation stages as 3110, 1450, 1773 and 2510 kg.ha-1, respectively. These results showed that role of antioxidant enzymes on reduction of lipid peroxidation and increasing the drought tolerance is more than proline. Also, an effective antioxidant system along with lower malondealdehyde and high silique number per secondary branch had the greatest role to productivity maintenance of Rapeseed under drought stress conditions.