Effects of Nitrogen Level and Seeding Density on Seeding Quality of indica-Type Super-High Yielding Hybrid Rice

In order to investigate the effect of nitrogen level,seeding density and seedling age on seedling quality of rice,a two-factor experiment including four N levels(10.3,20.7,31.0 and 41.4 g/m2)and four seeding densities(353,706,1059 and 1412 plants/m2)was conducted at Taoyuan town,Yongsheng county,Yunnan Province.Dynamic of leaf age,tiller number,dry weight,leaf SPAD value of seeding and leaf area index(LAI)in seedling nursery were investigated using an indica hybrid rice,Xieyou 107 as material.The low seeding densities or high N levels decreased the effective accumulated temperature for leaf emergence on stem and accelerate the leaf emergence,especially for seeding densities;Tiller number per seedling decreased with the development of seedling under high seeding density or low N level,whereas increased till 27 days after sowing then decreased under low seeding densities or high N levels;Nitrogen application promoted the emergence of new tillers,the maintenance of tiller with more than three leaves and the increase of LAI in seedling nursery,dry weight and N content of plant;The increased seeding density had negative effects on seedling quality indices,including the emergence of new tillers,the maintenance of tillers with more than three leaves,dry weight and N content of plants whereas showed positive effects on the LAI of seedling nursery,and the effects were more obvious than nitrogen treatments.