Characteristics Of Carbon And Nitrogen Metabolism In Early-maturing Rapeseed

Because of the increasingly conflict between rice and rape, the benefit of rapeseed is less than rice, most farmlands in the rape-rice-rice cropping system areas of southern China often become fallow fields in winter. Breeding of early-maturing rapeseed and researching of high-yielding cultural techniques is very important for the development of fallow fields and rapeseed production. Carbon and nitrogen metabolism were the main metabolic pathways in the rapeseed, the balance of carbon and nitrogen determined the relationship between vegetative growth and reproductive growth. In our research, pot and field experiments were designed to investigate the growing characteristics, processes of nitrogen distribution, physiological and biochemical characteristics of carbon and nitrogen metabolism. The main results were shown as following:1. Phenophase of two early maturity varieties (Zhongyou116, L01) and mid-late maturity (Zhongshuang11) was recorded. The results showed that:the duration of growth stages of different rapeseed varieties were different. Compared with mid-late maturity, early maturity varieties presented short seedling period and podding period, long stem elongation period and flowering period. Through analysis of the seed dry weight, moisture content and color during the pods development, the results showed that seed moisture content decreased rapidly, seed dry weight reached maximum level rapidly, seed color changed from green to light brown for Zhongyou116.2. The distribution of the nitrogen absorbed at the different periods of different maturity rapeseed varieties were studied using15N trace method under the pot experiment. Results showed that leaves played an important role in nitrogen redistribution, Zhongyou116had the large proportion of nitrogen transferringto flowers and seeds at all growing stages, meanwhile, it had the large redistribution proportion of nitrogen from leaves to other organs. The transferring proportion of nitrogen absorbed at flowering stage and podding stage to seeds in Zhongyou116was higher than that in Zhongshuang11. The speed of nitrogen redistribution in Zhongyou116was faster than Zhongshuang11.3. The key enzyme activity of carbon and nitrogen metabolism was evaluated, the results showed that the carbon metabolism of early maturity rapeseed was blooming during the flowering stage, but the nitrogen metabolism was inhibited. At the flowering stage, the GS activities of leaves for Zhongyou116were lower than that in mid-late maturity, but the SPS activities were higher. At the podding stage, the SS activities of leaves for Zhongyou116were lower than that in Zhongshuang11, and the GOGAT activities were higher during the early period of pod development, then lower than Zhongshuang11during the later period of pod development. Nitrogen transferred to seed quickly for Zhongyou116.4. The total nitrogen and soluble sugar content in the leaves of Zhongyou116were higher than that of Zhongshuang11during the seedling stage. Compared with Zhongshuang11, the leaves of early maturity rapeseed had higher total nitrogen content and lower soluble sugar content during the stem elongation stage. The total nitrogen and soluble sugar content in the leaves of Zhongyou116were lower than that of Zhongshuang11during the flowering stage and podding stage. The C/N of Zhongyou116was significantly lower than that of Zhongshuang11during the flowering stage and podding stage, we could find that Zhongyou116was blooming during the seedling stage and leaves accumulated large amounts of photosynthetic product. At the later growing stage, soluble sugar content of Zhongyou116decreased fastly, thus it can be seen, the photosynthetic product in leaves of Zhongyou116transferred to silique quickly to ensure the needs of reproductive growth and early maturity.