Effect Of Carbon-Nitrogen Accumulation And Carbon Transfer Redistribution In Productive Stage On Yield And Quality Of Brassica Campestris L.

In order to reveal the mechanism of high-NUE(nitrogen use efficiency) Brassica napus coordinates the contradiction of carbon and nitrogen metabolismand promotes oilformation, soil culture experiment was used with two Brassica napus genotypes which have different NUE(H represents high NUE genotypes,and L represents low NUE genotypes) that under the condition of normal N and limited N levels to study the following contents:(1) Difference of nitrogen accumulation, NUE and nitrogen harvesting index in harvesting stageof different Brassica napus genotypes; (2) Differences of carbon accumulation and distribution in organs of different Brassica napus genotypes in different growth stages (bolting stage, floweringstage,silique stage and harvesting stage) and C distribution from vegetative organs to into reproductive organs in reproductive stage; (3)Influenceof regulation enzymeinhibitorson carbon and nitrogen metabolism.The results showed that:(1)Nitrogen accumulation,NUE and nitrogen harvest index of H which reaches 2.32g/plan、9.94、0.44(normal-N) and 1.14g/plant、12、0.49(limited-N)was higher than that of L in harvesting stage, which was significant under limited nitrogen level,normal nitrogen level and the two nitrogen levels,respectively.(2)There is no differences of C accumulation amount between H and L, while the differences of C accumulation amount in different N application levels was significant, C accumulation amount of normal-N was significant higher than that of limited-N. C allocation proportion in roots and leaves of H was higher than that of L at former growth stages, and C allocation proportion in silique and grain of H was higher than that of L at later growth stages. While, C allocation proportion in stem of H was lower than that of L at whole growth stages, and C allocation proportion in root of H was lower than that of L at silique stage and harvesting stage.(3)The resluts of C distribution from vegetative organs to into reproductive organs in reproductive stages howed that, carbon redistribution of L stems in flowering stage and in harvesting stage was higher than that of H under normal-N, and the difference was significant in harvesting stage. Carbon redistribution of stems and flower in flowering stage, stem in silique stage and stem and silique peel in harvesting stage showed that H was higher than that of L under limited-N,but only the differences between stems in flowering stage and silique peel in harvesting stage was significant. It conversed in the other growth stages, the differences in grain yield were significant in harvesting stage, and the trend of carbon translocation and redistribution is also consistent. N application can promote C distribution from vegetative organs to into reproductive organs, the ratio of carbon translocation and redistribution to the reproductive organs of the two nitrogen application treatments of H was significant,which was not significant among different organs in different growth stages. Proportion of carbon redistribution to silique of L showed that normal-N was siginificantly higher than limited-Nin silique stage,while it was not significant in other growth stages.(4)The 50% percentage of C accumulation at stem elongation stage was left from vegetative organs, which was corresponding with redistribution proportion into reproductive organs. C reduction proportion of H was high than taht of L between limit-and normal-N, which improved 12.8%(limited-N) and 27.0% (normal-N), but C reduction proportion is significantly higher than C re-distribution proportion, which was because of the carbohydrate respiration consumption.(5)Regardless of the nitrogen supply level, PEPC and SPS activity of husk and grain of H were higher than that of L, the significant different of SPS activity in grainswas occurred under normal-N.Nitrogen application has increased PEPC activity of silique and grain during silique stage, which reversed for SPS. Enzymes activity wereboth decreased of two genotypes under inhibitor, but more influence for SPS activity of H.(6)The free amino acids and soluble sugar content in grain of H were high than that of L under normal-and limited-N. Nitrogen application increased free amino acids content of husk and grain, but has different influence to soluble sugar which increased in husk and dercreased in grain. Compared with CK(treatment of painted water on slique), PEPC and SPS inhibitor has different effect on free amino acids and soluble sugar content of grain, which decreased under normal-N and reversed under limited-N for free amino acids and improved under PEPC inhibitor and declined under SPS inhibitor for soluble sugar.(7) Grain oil content of H was slightly higher than that of L, but the difference of the two nitrogen supply levels did not reach a significant level. Oil production of H was significantly higher than that of L,compared to limited-N treatment, Grain oil content of normal-N decreased slightly while the Oil production increased significantly.There was no significant difference in carbon accumulation of brassica napus with different NUE in the whole growth stages,however, H not only maintained the high nitrogen accumulation and NUE but transport more carbon accumulated in vegetative organs to grain in reproductive stage;on the other hand,emzyme regarding carbon and nitrogen metabolism of H was advantageous in silique,which can strive for more resources to promote grain formation,besides,provide favorable conditions to alleviate the contradiction between carbon and nitrogen metabolism, and promote the formation of oil.