Balance And Regulation Of Hormones Of High Harvest Index Rapeseed(Brassica Napus L.) In Different Environments

Brassica napus L. was derived from interspecific hybridization and subsequent chromosome doubling between B.rapa and B.oleracea. As the most widely cultivated oil crop in China, rapeseed ranks first both area and total production around the world, but its supply is far less than demand in our country. For this reason, improving the production is the eternal goal in rapeseed breeding.In this experiment, three rapeseed types were planted in high production region(Yunnan) and major producing region(Chongqing). In order to explore the mechanism of high yield and high harvest index rapeseed and high yield rapeseed in Yunnan, we compared the differences of absolute content, relative content and the balance ratios of endogenous hormones in eight rapeseed parts both between Yunnan and Chongqing and among three rapeseed types. Besides, the effects of exogenous hormones on pod and seed were also studied. The results showed that:1. Yield and HI of three rapeseed types had very significant differences in Yunnan and Chongqing. The yield of rapeseed types in Yunnan was significantly higher than that of rapeseed types in Chongqing, while the HI was less than that of rapeseed types in Chongqing.2. Relationships between yield, HI and endogenous hormones among various types were similar. Yield had very significantly negative correlation with ABA/ZR in leaves and seeds, and IAA/ZR in pod skin; having very significantly positive correlation with IAA/ZR and IAA/ABA in seeds. HI had very significantly negative correlation with ABA/GA3 in leaves, IAA/GA3 in pod skin and ABA/BR in seeds, having significantly negative correlation with IAA/BR in flower bud of main brance. Yield and HI of Yunnan materials had more significant correlation with the ratios of hormones on lateral branches, while that of Chongqing materials had more significant correlation with that on main branch.3. Yield difference of three rapeseed types in Yunnan and Chongqing had very significantly positive correlation with ZR/ABA in leaves, IAA/ABA in flower buds of lateral brance, ZR/BR in pod skins and with IAA/ZR and IAA/ABA in seeds, having significantly negative correlation with GA3/BR in stem, ABA/BR in flower buds of lateral brance and ABA/ZR in seeds.4. In the exogenous hormones treatment experiment, all kinds of treaments promoted the growth of pod and seed. Compared with CK, length, width, superficial area, pod productivity and thousand seed weight were improved, except for a few. As for length of pod, the average increase of low HI Brassica napus L. was higher than that of high HI Brassica napus L.in single hormone treatment, while lower in mixed hormones treatment. For width of pod, the average increase of high HI Brassica napus L. was higher than that of low HI Brassica napus L. in single hormone treatment, while lower in mixed hormones treatment. In terms of superficial area, pod productivity and thousand seed weight, the average increase of high HI Brassica napus L. was higher than that of low HI Brassica napus L.in single hormone treatment, while lower in mixed hormones treatment. No matter which kind of treatment, the average increases of length, width and superficial area on upper branch pod were higher than that on lower branch; these treatments had more effects on width of pod, compared with length of pod. In single hormone treatment, three indexes of pod productivity and thousand seed weight on upper branch showed higher average increases than that on lower branch. However, in mixed hormones treatment, three indexes of pod productivity and thousand seed weight on upper branch showed lower average increases than that on lower branch. In all treaments, NAA0.1mg/L+6-BA20mg/L, NAA0.1mg/L and 6-BA20mg/L had most obvious effect. Thousand seed weight was very significantly higher than CK, but other indexes had no significant difference.