Abstract:

Yellow-seeded rapeseed (Brassica napus L.) is characterized with thinner seed coat and lower hull percentage, which in turn is correlated with higher oil, protein and lower crude fiber contents compared to black-seeded rapeseed from the same genetic background. The breeding of yellow-seeded rapeseed has become one of the main objectives in rapeseed breeding. However the growth vigor, resistance and yield of yellow-seeded rapeseed are not so good as black-seeded rapeseed. The growth vigor of rapeseed plants during seedling stage is in connection with its yield significantly. Two pairs of different genetic near-isogenic lines of yellow-seeded and black-seeded rapeseed (Brassica napus L.) genotypes were used to study the physiological characters of yellow-seeded rapeseed in seedling stage, which included photosynthetic characters, characters on C/N metabolism and accumulation of dry matter. The results showed that the chlorophyll content and carotenoid content of yellow-seeded rapeseed were lower than those of black-seeded rapeseed, and its net photosynthetic rate was lower compared to black-seeded rapeseed from the same genetic background. The leaf area index (LAI) of yellow-seeded rapeseed was lower than that of black-seeded rapeseed. It was found that there were higher total sugar content and lower protein content in yellow-seeded rapeseed plants than in black-seeded rapeseed plants in every plant organs during seedling stage, and there were lower nitrogen content and activity of nitrate reductase in yellow-seeded rapeseed plants than in black-seeded rapeseed plants at overwintering stage. Width of root colla and dry matter per plant in yellow-seeded rapeseed plants were also lower than those in black-seeded rapeseed plants, indicating the weak growth vigor of yellow-seeded rapeseed. All those above were the important reasons leading to the lower yield of yellow-seeded rapeseed.

Key words: Yellow-seeded rapeseed (Brassica napus L.), Physiological characters, Seedling stage