Effects Of Nitrogen Application On Growth And Development Of Late Japonica Rice In Red Soil

In this study,the effects of nitrogen application on the growth and development of late Japonica Rice in red soil paddy field—Yong you 2640 and Nan jing 46,were studied by setting different nitrogen fertilizer levels(0,195,240,285 and 330 kg/ha pure nitrogen,using N000,N195,N240,N285 and N330 to express respectively)and different nitrogen application experiments(pure nitrogen 240 kg/ha was applied,the proportion of tiller and panicle is 5:5:0?5:4:1?5:3:2?5:2:3 and 5:1:4,using N1?N2?N3?N4?N5 to express respectively).The main results are as follows:1.Effects of different nitrogen application rates on growth and development of late Japonica Rice in red soil paddy field(1)With the increase of nitrogen application rate,the yield of Yong you 2640 and Nan jing 46 was first increased and then decreased.When the highest yield was reached,the nitrogen application rates of the two varieties were different,Yong you 2640 was N 285,and Nan jing 46 was N 240.(2)The number of tillers,which have a high nitrogen application rate was large and have a lower decline later.It will raised with the increase of nitrogen application rate.Tiller number of Southern japonica 46 reached the peak after transplanting for 20 days while Yong you 2640 after transplanting for 25 days.The rapid accumulation period of N for Southern japonica 46 was from tillering to jointing stage while Yong you 2640 was from jointing to full heading stage.(3)With the increase of nitrogen application rate,the leaf area index and SPAD value of the two varieties showed an increasing trend,and the rate of decline slowed down in the late growth stage.(4)With the increase of nitrogen application,nitrogen utilization rate in Yong you 2640 and Nan jing 46 showed an increasing trend,the mean value of the former one is 31.2%,and the latter is 16.8%.2.Effects of different nitrogen application on growth and development of late Japonica Rice in red soil paddy field(1)The highest yield of Yong you 2640 reached 11.4 t/ha,which exceeding the lowest yield of 8.84 t/ha of 28.9%,while the highest yield of Nan jing 46 reached 9.2 t/ha,which exceeding the lowest yield of 7.19 t/ha of 27.9%.The yield of late Japonica Rice in red soil paddy field raised with the increase of fertilizer application,The specific performances are as follows: N4>N3>N5>N2>N1.(2)Under different nitrogen application modes,the total number of tillers was high in the early stage and decreased slowly with the increase of fertilizer application.The decline rate of tiller number of Yong you 2640 was higher than Nan jing 46,however the tillernumber in late growth stage was lower than Nan jing 46.(3)Application of nitrogen fertilizer in later stage can increase yield,the leaf area index and SPAD value decreased slowly after full heading with a smaller amplitude.(4)Under different nitrogen application modes,nitrogen uptake and utilization rate raised with the increase of nitrogen application rate and reached to the highest value in N5.The highest nitrogen uptake and utilization rate of Yong you 2640 was 33% higher than the average while Nan jing 46 was 112% higher than the average.