Abstract: 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.

Key words: nitrogen, seedling density, seedling age, hybrid rice, seedling quality

摘要： 2007年在云南省永胜县涛源乡水稻特殊高产生态区，利用杂交籼稻组合协优107，设计了氮肥处理（10.3、207、31.0和41.4 g/m2N）和秧苗密度处理（353、706、1059和1412苗/m2）双因子试验，旨在探讨施氮水平、秧苗密度和秧龄对超高产杂交籼稻秧苗素质的影响。结果表明：1)秧苗密度降低或施氮量增加，均降低出叶所需的有效积温，加快秧苗的出叶，且秧苗密度的效应更显著；2)高密度或低氮条件下，秧苗单株带蘖数随着秧龄的增加有减少的趋势；而在高氮或低密度条件下，秧苗单株带蘖数在播种后27 d（7叶期）内呈增加趋势，之后进入分蘖衰减期；3)施氮对秧苗新分蘖的发生和大分蘖保持、苗床叶面积指数的增大、单株干质量的增加以及植株含氮量的提高均有正效应；4)秧苗密度对秧苗新分蘖的发生和大分蘖保持、单株干质量的增加均有负效应，并比氮效应明显；对植株含氮量的提高也有一定的负效应；对苗床叶面积指数的增大有正效应。

关键词: 氮素, 秧苗密度, 秧龄, 杂交水稻, 秧苗素质