[目的]研究直播稻(Oryza sativa L.)播种密度对产量结构及植株茎秆性状的影响,探讨直播稻高产稳产适宜的播种密度.[方法]以中熟中粳连粳7号作为试验品种,按基本苗的不同,设5种密度水平,分别是90万、120万、150万、180万、210万株/hm2,随机区组排列,重复3次.[结果]随着播种密度的增加,有效穗数总的趋势是上升的,但种植密度对有效穗的调控作用较小,每穗总粒数、颖花结实率和千粒重总的趋势是下降的,基本苗105万株/hm2左右时较适宜.基本苗90万株/hm2处理,植株茎秆第1、2节间长度最短,占茎秆长度的比例最小,第3、4、5节间长度最长,占茎秆长度的比例最大,茎秆重量、粗度及单位长度重量均最大,茎秆单位长度重量承担的稻穗重较小,茎秆抗倒伏力最强.[结论]从高产稳产两方面考虑,直播稻连粳7号基本苗90万～ 105万株/hm2最佳.%[ Objective] The purpose was to study the effects of planting density on rice yield structure and plant stem characters when sowing directly, discuss their suitable planting density to realize high yield and stable yield. [ Method] Choosing late maturity and medium japonica rice Lianjing No. 7 as test variety, 5 density levels, 90 x 104, 120 xlO4, 150 x104, 180 x 104, 210 x 104 plants per ha, were designed and randomized block arrangement was used with 3 repeats. [Result] On a whole, with planting density increased, effective panicles number rose, while spikelets number of per panicle, spikelet fruiting rate and 1 000-grain weight decreased, but planting density had a little regulatory functions to effective panicles number, and the suitable basic seedling number was 105 x 104 plants per hm2. When basic seedling number was 90 X 10 plants per hm , length of first and second internodes were both the shortest, and were both the smallest of their proportion of whole stem length; Length of third, fourth and fifth internodes were all the longest, and were all the biggest of their proportion of whole stem length; Stem weight, diameter and weight per centimeter were all the biggest, and weight of rice ears bearing by stem weight per centimeter was smaller, and resistance to lodging of stem was the strongest. [Conclusion] Considering from high yield and stable yield, the best planting density of direct sowing rice Lianjing No. 7 is 90 x 104 - 105 x 104 plants per ha.
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