Effect Of N Fertilizer Application On Nitrogen Metabolism And Nitrogen Use Efficiency Of Japonica Rice Under Cold Water Stress

Low temperature damage in rice have occurred, and the loss of resulting the yield of japonica rice in cold region can not be ignored. Reasonable application of nitrogen fertilizer can benefit to the stable yield of crops, and then improve economic efficiency. In this test, Dongnong 428, Songjing 10 and Longdao 7 were fieid-grown as material. Under cold water stress at tillering stage setting seven levels of nitrogen application, study on the influence of N fertilizer application on nitrogen metabolism and nitrogen use efficiency of japonica rice in cold region under cold water stress at tillering stage, to determine the theoretical basis for the appropriate application of nitrogen fertilizer of japonica rice in cold region in cold water stress. The main conclusions of this experiment are as follows:(1) Under cold water stress at tillering stage, the activity of NR, GS, GOGAT for functional leaves of japonica rice in cold region during whole growth stages showed a single-peak curve. The peak is all at full heading stage, and the activity of GDH showed the trend of high-low-high-low. As the nitrogen application increasing, it is a maximum for the activity of NR for the three varieties at N150. For Dongnong 428, there is a maximum for the activity of GS at N150, and the maximum at N175 for Songjing 10 and Longdao 7.For Dongnong 428 and Longdao 7,there is a maximum for the activity of GOGAT at N150,and the maximum at N175 for Songjing 10.For Dongnong 428,there is a maximum for the activity of GDH at N200, and the maximum at N175 for Songjing 10 and Longdao 7.In the same amount of nitrogen treatments,the activity of NR for the three varieties is Songjing 10>Dongnong 428>Longdao 7, the activity of GS、GOGAT、GDH is Dongnong 428>Longdao 7> Songjing 10.Under cold water stress at tillering stage, the activity of GOT、GPT for functional leaves of japonica rice in cold region showed a single-peak curve.The peak is all at booting stage.As the nitrogen application increasing, the activity of GOT、GPT showed first increased and then decreased.It is a maximum for the activity of GOT、GPT for the three varieties at N175. In the same amount of nitrogen treatments, the activity of GOT、GPT for the three varieties is Dongnong 428> Songjing 10 > Longdao 7.(2) Under cold water stress at tillering stage, the soluble protein content for functional leaves of japonica rice in cold region showed a single-peak curve. The maximum is at booting stage. As the nitrogen application increasing, the soluble protein content showed first increased and then decreased. It is a maximum for the soluble protein content at N150. In the same amount of nitrogen treatments, the soluble protein content for the three varieties is Dongnong 428> Longdao 7 >Songjing 10.(3) Under cold water stress at tillering stage, the nitrogen rate of japonica rice in cold region declined with the passage of growth stages. As the nitrogen application increasing, the nitrogen rate showed first increased and then decreased. It is a maximum for the nitrogen rate at N175. In the same amount of nitrogen treatments, the nitrogen rate for the three varieties is Longdao 7> Dongnong 428>Songjing 10.(4) Under cold water stress at tillering stage,the plant nitrogen uptake content of japonica rice in cold region increased with the passage of growth stages, and the maximum is at mature stage. As the nitrogen application increasing, the plant nitrogen uptake content increased.It is a maximum for the plant nitrogen uptake content at N225.In the same amount of nitrogen treatments, the plant nitrogen uptake content for the three varieties is Dongnong 428>Longdao 7>Songjing10.As the nitrogen application increasing, the nitrogen rate in the grain from vegetation showed first increased and then decreased. The maximum is at N125,then declined.In the same amount of nitrogen treatments, the nitrogen rate in the grain from vegetation for the three varieties is Songjing 10>Longdao 7>Dongnong 428,but the nitrogen rate in the grain from underground roots for the three varieties is Dongnong 428>Longdao 7>Songjing 10.(5) With the increase of amount of N Fertilizer Application, the nitrogen uptake and utilization of Japonica Rice in cold region under cold water stress at tillering stage showed a trend of first rising and then decreasing,which in the N125 treatment Dongnong 428 and Longdao 7 showed the highest values, in the N100 treatment Songjing10 showed the highest values,In the same nitrogen treatment, the nitrogen uptake and utilization, physiological utilization and agricultural utilization of three cultivars showed Dongnong 428> Longdao 7> Songjing 10.(6) The grain protein content of Japonica Rice under cold water stress at tillering stage showed the trend of first decreasing and then rising. In the N175 treatment, the grain protein content of the three cultivars reached the highest values. In the same nitrogen treatment, grain protein content of three cultivars was Songjing10> Longdao 7> Dongnong 428.(7) Yield increased with the increase of N Fertilizer Application, showing the trend of first increasing and then decreasing. In the N100 treatment, the yield of 100kg/hm2 was the best.