Effects of exogenous ABA and BR on waterlogging resistance of juvenile rapeseed

Pot experiment was conducted to investigate the effects of exogenous application of abscisic acid(ABA) and brassinolide(BR) on waterlogging tolerance of juvenile rapeseed(Brassica napus L.cv Zhongshuang 9).Results showed that short-term waterlogging(0 to 12d) promoted the growth of juvenile rapeseed,while long-term waterlogging(18d) inhibited the growth.Foliar spraying with ABA(75.67μmol/L) and BR(0.21μmol/L) significantly alleviated the injuries of long-term waterlogging stress,and respectively increased 19.52% and 26.22% of the dry weight compared to that of single waterlogging treatment.Furthermore,ABA and BR treatment alleviated chlorophyll degradation and increased leaf soluble sugar contents,photosynthetic rate,as well as superoxide dismutase(SOD),peroxidase(POD) and catalase(CAT) activities,but decreased malondialdehyde(MDA) content.The results indicated that foliar spraying with ABA and BR could alleviate the negative influence of waterlogging on rapeseed seedlings.