Abstract:

 To better understand the mechanism of waterlogging on direct-seeded rapeseed (Brassica napus L.), changes of rapeseed cultivar Fengyou 737 during radicle period were investigated after waterlogging by 4 regulators pretreatments. The 4 regulators were AOA [O-(carboxymethyl) hydroxylamine hemihydrochloride, for soaking], GA3 (gibberellic acid, for soaking), PP333 (paclobutrazol, for soaking), and 1-MCP (1-methyl-cyclopropene, for fumigat? ing imbibed seeds). Results showed that, waterlogging at the radicle growth significantly reduced the seedling emer? gence rate and emergence index, and inhibited the seedling growth. The pretreatments with AOA, 1-MCP and GA3 effectively relieved the waterlogging stress on rapeseed emergence, among them the pretreatment of AOA
showed relatively higher promotion to seedling growth. The pretreatment of PP333 reduced the waterlogging stress on rapeseed emergence. After waterlogging for 24 hours, the cell autophagic activity increased in germs of seeds pre? treated with AOA, which could be helpful to improved stress adaptation. The pretreatments of 1-MCP, AOA and GA3 reduced ethylene release rate in seeds under non-waterlogging condition but decreased the falling range of eth?
ylene release after waterlogging for 24 hours. It indicated that lowering endogenous ethylene production prior to wa? terlogging but maintaining ethylene production to certain degree might be conducive to waterlogging tolerance of rapeseed at radicle growth period.

Key words:  , rapeseed (Brassica napus L.)；waterlogging resistance；radicle growth；ethylene release rate；cell autophagy