Preliminary Study On Different Responses To N Fertilizer Of Zhongyouza 12 And Its Parents

Reasonable nitrogen(N)fertilizer application plays a key role in improving the yield and N fertilizer utilization of oilseed rape.A large amount of N is essential for oilseed rape growth,while the utilization efficiency of N is low,with the average N fertilizer utilization rate of 34.2%in the mainly area of winter oilseed rape cultivation.In general,hybrids have obvious advantages in yield,but it is not clear whether they have heterosis in N absorption and utilization.In order to explore the advantages of hybrid in the utilization of N and exploit the potential of high-efficiency utilization of N in oilseed rape,Zhongyouza 12 and its parents were used as the research materials.Field experiments in continuous three years were conducted,studying the effects of different N application rates on the yield,yield components,dry matter and N accumulation of the three varieties,to identify the potential of N utilization of hybrid oilseed rape,which were analyzed from the perspectives of N transport and photosynthetic physiology.The main findings are as follows:1 N application significantly increased the yield,yield components,dry matter and N accumulation of hybrid oilseed rape and its parents.Zhongyouza 12 had a higher yield potential than the parents,with the platform yields of 2855 kg/hm~2,2303 kg/hm~2 and2039 kg/hm~2,respectively.The number of pods per plant in Zhongyouza 12 was significantly higher than that of the parents,and the 1000-grain weight is significantly higher than that of its male parent,but no difference with the female parent.2 N use efficiency of hybrid oilseed rape and its parents decreased as the N application rate increased.The N apparent utilization efficiency of Zhongyouza 12 was significant higher than that of the male parent,following with female parent.The N physiological utilization efficiency of Zhongyouza 12 was significantly higher than that of male parent,but no difference was observed between Zhongyouza 12 and the male parent.The N fertilizer rates were 227.3 kg/hm~2,180.4 kg/hm~2 and 217.0 kg/hm~2,respectively,of Zhongyouza 12,male and female patern to achieve the platform yield.To get the yield level of platform yields in the parents,Zhongyouza 12 saved an average of 21.7 kg/hm~2 and 90.9 kg/hm~2 of N fertilizer,compared to its male and female parent,respectively.N accumulation showed a significant difference between Zhongyouza 12>male parent>female parent,indicating that hybrid rape can make full use of absorbed N in the case of low-N fertilizer input,and achieve high yield and N fertilizer utilization.3 That Zhongyouza 12 had higher N use efficiency was attributed to its enhanced capacity of N absorption and transportation.N fertilizer application significantly increased N transport from stems,leaves and roots to pod and the N accumulation in the reproductive organs post-anthesis.The N translocation rate amount of the vegetative organs of Zhongyouza 12 was significantly higher than that of their parents with no N application,The post-anthesis N accumulation and stem N translocation rates of Zhongyouza 12 were significantly higher than that of the female parent,and had no difference with the male parent.N translocation rates in leaf and root in Zhongyouza 12was significantly higher than that of the male parent,and same with the female parent.Hybrid oilseed rape had obvious heterosis in N use efficiency,for the higher ability of N absorption and translocation than its parent.4 The photosynthetic N efficiency of Zhongyouza 12 was significantly higher than that of the parents.When the amount of N fertilizer belows180 kg/hm~2,N fertilizer increase increased the net photosynthetic rate of rape seedling leaves,reduce the heat dissipationand the canopy temperature.The net photosynthetic rate and photosynthetic N efficiency of Zhongyouza 12 and the male parent were significantly higher than those of the female parent.In addition,Zhongyouza 12 had higher potential of photo-energy absorption and photoprotection than its parents,thus,the hybrid could obtain higher photosynthetic efficiency under a limited N supply and achieved greater production.