| Nitrogen utilization efficiency is an important research topic in the process of rice production,so it is very important to improve rice nitrogen utilization rate in rice production.Four japonica rice cultivars,which were mainly promoted in Jilin Province,were considered as material in this experiment.By conducting field experiment at four nitrogen conditions were 0N(no nitrogen),1N(nitrogen 70kg·hm-2),2N(nitrogen 140kg·hm-2)and 3N(nitrogen 210kg·hm-2)to study the effects of plant type,agronomic traits,photosynthetic capacity,physiological indexes,yield and constituent factors.And the nitrogen utilization efficiencies of four japonica rice under four nitrogen levers were researched.the results showed:1.With the increasing of nitrogen levels,plant height of four japonica rice cultivars had no significant increase from tillering period to jointing period,but plant height had significant rise at high nitrogen levels(2N,3N)in heading date.The effect on the first internode length of four japonica rice cultivars was significantly greater than that of the second and third sections with the nitrogen levels.The leaf area of Jinongda 505,Jinongda 603,Jinongda 809 were significantly increased at the high nitrogen level(2N,3N).There were no significant increases in leaf angle and tiller number with the increase of nitrogen level in jinongda 505,Jinongda 809,Jinongda 815.The plant type showed that the plant height was higher,the degree of leaf curvature was large,and the tiller number became more with the increase of nitrogen.2.High nitrogen levels(2N,3N)promoted the increase of chlorophyll content in four japonica rice cultivars during grain filling stage.The increase of net photosynthetic rate(Pn)of blade performed,flag leaves> down two leaves> down three leaves.The net photosynthetic rate(Pn)of flag leaves and down two leaves of Jinongda 505,Jinongda 603 had had no significant change.The Pn of down two leaves and down three leaves reached higher value at 2N of Jinongda 809.3.The activity of SOD had no significant difference in Jinongda 505,Jinongda 603,Jinongda 815 in grouting period with the increasing of nitrogen levels.The activity of SOD of Jinongda 815 down three leaves reached the higher value at 1N level.The effect of nitrogen on the activity of POD in 2N level of Jinongda 603 was significant.The activity of POD in the low nitrogen level(0N,1N)was significantly higher than that in the high nitrogen level(2N,3N).The content of POD of down two leaves and down three leaves reached the higher value at 1N level in Jinongda 815.The CAT enzyme activity of four japonica rice varieties had higher response tonitrogen in low nitrogen level(0N,1N).The content of soluble protein in flag leaves and down two leaves of four japonica rice varieties had no significant increasing with the increase of nitrogen level.The soluble sugar content of four japonica rice varieties had advantages in low nitrogen level(0N,1N).4.The nitrogen content and nitrogen uptake of four japonica rice varieties increased with the increase of nitrogen.However,nitrogen utilization rate of Jinongda 505 was the highest in 2N level,and nitrogen utilization rate of Jinongda 603 and Jinongda 815 increased with the augment of nitrogen content.The yield of Jinongda 505 and Jinongda 809 was the highest in 2N level,but the yield of Jinongda 603 was the highest in the 3N level.Moreover,the yield of Jinongda 815 was not significant variation at four nitrogen levels.The correlation between total nitrogen content and yield showed that there was a significant positive correlation between the total nitrogen content and the yield of various organ for Jinongda 603 and Jinongda 809,while total nitrogen content of stem had a significant positive correlation with the yield for Jinongda505,but the total nitrogen content of Jinongda 815 was positively correlated with yield but not significant.In summary,this study indicates that most of plant type and physiological characteristics of four japonica rice cultivars is on the rise with the increasing of nitrogen levels.But the plant type and physiological characteristics reached the higher value at 2 N of Jinongda505,3 N of Jinongda 603.Jinongda809 has no significant difference.Although Jinongda815 has little rise at 2 N level,it belong to nitrogen insensitive varieties.This experiment shows that nitrogen utilization rate of Jinongda 505 reached the highest value at 140kg/hm~2..Yield and nitrogen utilization rate of Jinongda 603 had the higher value at 210 kg/hm~2.Yield and nitrogen utilization rate of Jinongda 809 had the higher value over 140 kg/hm~2.Yield of Jinongda 815 had slight increasing at different nitrogen level,but nitrogen utilization rate of Jinongda 815 had no significant increases. |
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