Abstract:

Rapeseed is one of the most important oil crops in China. It often encounter with the high temperature and humidity or continuous raining at the maturity stage, which results in pre-harvest sprouting. Pre-harvest sprouting will cause the decrease of seed yield and quality. In order to screen out Brassica napus lines resistant to pre-harvest sprouting and elucidate the major factor(s) inhibiting pre-harvest sprouting，the rate of pre-harvest sprouting and germination of the freshly harvested seeds of the five Brassica napus lines including 832, 780, 1-1, 1-13, 8-6 were investigated under field conditions or under various stimulated conditions in laboratory, and the contents of the endogenous hormones abscisic acid (ABA), indole acetic acid (IAA), cytokinin (CK) in fresh seeds and shells were determined with high performance liquid chromatography (HPLC). The results showed that there were significantly different rates of pre-harvest sprouting among different lines under field condition and under various stimulated conditions in laboratory, but no significant difference in seed germination rate after five days of the germination text. The higher ABA content in shells the lower rate of pre-harvest sprouting. The ABA content in shells was significantly and negatively correlated with rate of pre-harvest sprouting (r=－0.8941). CK in shells could obviously increase the rate of pre-harvest sprouting while IAA in seeds could promote early seed germination. Treatments of seeds with ABA at different concentrations showed that ABA (20 mg L^-1) could effectively inhibit the seed germination.

Key words: Rapeseed (Brassica napus L.), Pre-harvest sprouting, Endogenous hormones