Effects Of Different Sowing Dates, Transplanting Densities And Nitrogen Fertilizer Application On Growth And Development And Yield Of Rape In Paddy Field

Rape (Brassica napus L.) is one of the main economic crops in Hunan province, which is very important for improve farmers’ economic income and living standard with large area development of rape production. The growth and development and yield of rape were effected by various cultivation factors, such as the seeding quantity, sowing date, transplanting methods, transplanting densities, different nitrogen fertilizer application and so on, which were important factors for growth and development and yield of rape plant. In order to explore the best sowing date and seeding quantity, transplanting methods, transplanting densities and nitrogen fertilizer application suitable for rapeseed in paddy field in Hunan province, a cultivar Xiangzayou6was used as the materials to investigate the effects of different sowing dates and seeding quantity, transplanting methods, transplanting densities and nitrogen fertilizer application on growth and development, biological characteristics and yield of rape plant in the present paper.1Analysis of growth stages, yield components and yield of rape in paddy field with different sowing datesThe sowing dates experiments showed that the sowing dates suitable for rapeseed in paddy field was from September30to October5, and the best sowing date was October5.Analysis of the duration time of different growth stages with different sowing dates treatments were showed that the variation of duration time from initial bloom stage to end flowering and from end flowering to maturity was small, but the variation amplitude at seedling and elongation stage of rape was larger. That is, in the early growth stages of rape were easy affected by different sowing dates in the middle and lower Yangtze area.With the sowing time delayed, yield related traits such as the height of plant, longer main inflorescence, the effective branching number per plant, greater silique number per plant, seed per pod and1000-seed weight were reduced, and the yield of rape were reduced also.2Comparing of yield components and yield of rape in paddy field with different seeding quantityAnalysis of the correlation between yield components and yield of rape and different seeding quantity were showed that the best seeding quantity for directed sowing rapeseed in paddy fields with tillage free was3.0kg·hm-2, which was can be get the highest yield of rape.With the sowing quantity increased, yield related traits such as the height of plant, longer main inflorescence, the effective branching number per plant, seed per pod and1000-seed weight were reduced, and the yield of rape were reduced also. Among the four treatments, the yield of rape with seeding quantity3.0kg·hm-2treatment was the highest, which significantly higher than other treatments. Compared with the other treatments, the yield of rape with seeding quantity3.0kg·hm-2treatment was increased by10.39%,18.91%and25.23%, respectively. And the yield of rape with seeding quantity3.75kg·hm-2treatment was the better. Compared with seeding quantity4.5kg·hm-2and5.25kg·hm-2treatments, the yield of rape with seeding quantity3.75kg·hm-2treatment was increased by7.72%and13.44%, respectively.3Biological characteristics and yield traits of rape in paddy field with different sowing and transplanting patternsCompared with directed sowing rapeseed in paddy fields with tillage free (DSRT, CK), the height of plant, open quotation diameter, length and width of the biggest leaf, numbers of leaf, numbers of green leaf, diameter of root collar and dry biomass per plant of rape plant were increased by seedling transplanting with tillage treatment (STTT) and seedling transplanting with spiral tillage treatment (STST) at seedling. At flowering stage, leaf area per plant and leaf area index of rape with STTT and STST were higher than that of the DSRT. At flowering stage and maturity, dry weight of root per plant, dry weight of stem per plant, dry weight of laves per plant and dry yield of plant were increased by STTT and STST. The results showed that the height of plant, longer main inflorescence, the first and second number of branch, effective number of pod of main inflorescence, greater silique number per plant, seed per pod and1000-seed weight were increased by STTT and STST. But the height of the first effective number of branch was increased by DSRT. The yield of rape with STTT and STST was increased by18.49%and11.51%, compared with the DSRT, respectively.4Analysis of growth and development and yield of rape with different transplanting densitiesThe results indicated that the primary growth stages of rape plant were earlier than expected with transplanting densities increased under the same nitrogen fertilizer application condition. At flowering stage, the leaf area per plant and leaf area index of rape plant were decreased with the transplanting densities increased. At flowering stage and maturity, the dry weight of root per plant, dry weight of stem per plant and dry weight of laves per plant were decreased with the transplanting densities increased.Under the same nitrogen fertilizer application condition, the height of plant, longer main inflorescence, the first and second number of branch, effective number of pod of main inflorescence, greater silique number per plant, seed per pod and yield per plant with lower transplanting densities treatment were higher than that of the higher transplanting densities treatment. And the yield of rape was decreased with transplanting densities improved. Compared with the control, the yield of rape with different treatments was113.22%,83.24%,125.18%,186.16%,169.49%and156.63%greater, respectively.5Analysis of growth and development and yield of rape with different nitrogen fertilizer applicationUnder the same transplanting densities condition, the dry weight of foot, dry weight of stem and dry weight of laves of plant with nitrogen fertilizer application180.0kg·hm-2treatment were higher than that of the nitrogen fertilizer application120.0kg·hm-2treatment at flowering stage and maturity. Meanwhile, the second number of branch, effective number of pod of main inflorescence, greater silique number per plant,1000-seed weight and yield of rape plant with nitrogen fertilizer application180.0kg·hm-2treatment were higher than that of the nitrogen fertilizer application120.0kg·hm-2treatment. The results indicated that the suitable amount of nitrogen fertilizer application was180.0kg·hm-2and the transplanting densities were15×104plants·-hm-2for gaining high yield of rape.