钵苗机插密度对不同穗型水稻品种产量、株型和抗倒伏能力的影响

选用3种穗型水稻品种,设置3种钵苗机插密度,以毯苗机插为对照(CK),系统研究钵苗机插不同密度对水稻产量及其构成、穗部性状、冠层叶系配置、茎秆物理特性和抗倒伏的影响,旨在探明水稻钵苗机插配套不同穗型品种适宜栽插规格及其增产特点;同时,阐明钵苗机插不同密度下水稻株型特征和抗倒伏特性。结果表明:(1)3种钵苗机插密度处理下,大穗型品种产量随密度降低呈先增后降的变化趋势,但均显著高于CK;中、小穗型品种产量有随着密度降低而下降的趋势。不同穗型品种穗数随着密度降低而显著减少,每穗粒数显著增加,结实率和千粒重无明显变化规律。(2)钵苗机插下不同穗型水稻品种的穗长、着粒密度、单穗重、一次枝梗数、二次枝梗数、一次枝梗粒数和二次枝梗粒数均随密度降低而增加,且高于CK;一、二次枝梗数比值和一、二次枝梗粒数比值随密度降低而呈下降趋势。(3)钵苗机插下不同穗型水稻品种的上三叶的叶长、叶宽、叶基角、披垂度和比叶重随着密度降低而呈增加趋势;且上三叶的叶长、叶宽和比叶重高于CK。(4)随着密度降低,不同穗型品种钵苗机插水稻基部N1、N2、N3节间长度减少,茎秆粗度、茎壁厚度和节间干重增加,穗下节间长、秆长、株高、重心高增加,而相对重心高有减小趋势。(5)不同穗型品种钵苗机插水稻基部节间N1、N2、N3抗折力和弯曲力矩随着密度降低而增加,倒伏指数呈下降趋势,且低于CK。说明水稻钵苗机插配套大穗型品种宜适当降低密度,增加每穗粒数以获高产;中穗型品种需兼顾穗数和每穗粒数,提高群体颖花量而增产;小穗型品种依靠穗数而提高产量。水稻钵苗机插降低密度能改善穗部性状和增加上三叶的叶面积,但增大了叶基角和披垂度,同时利于缩短基部节间长度,增加基部节间粗度、茎壁厚度和充实度,从而提高抗折力,降低倒伏指数。

Effect of Planting Density of Mechanically Transplanted Pot Seedlings on Yield,Plant Type and Lodging Resistance in Rice with Different Panicle Types

In order to identify the suitable planting density and high-yielding charcteristices of mechanically transplanted pot seedlings of rice (PS) with different panicle types, and clarify the effect of planting density on plant type and loding resitance, a field experiment was conducted using rice cultivar with three panicle types in 2012 and 2013. By setting high, medium and low planting density treatments and using mechanically transplanted carpet seedling as control (CK), we investigated yield and its components, panicle traits, canopy leaf system configuration, physical properties of culm and lodging resistance. Resluts showed as follows: (1) With decreasing planting density, yield of three density treatments in the large panicle cultivar increased firstly and then reduced which was higher than that of CK;,and yield of three density treatments reduced progressively for the medium and small panicle cultivar. With decreasing planting density, number of panicles in all cultivars reduced significantly, and spikelets per panicle increased markedly, but there was no significant difference in grain-filled percentage and 1000-grain weight. (2) With decreasing planting density, in all cultivars with PS, panicle length, grain density, grain weight per panicle, No. of primary branch, No. of secondary branch, No. of grains of primary branch and No. of grains of secondary branch showed a tendency of increase, and were higher than those in CK, but it showed a decreasing tendency in ratio of No. of primary branch to No. of secondary branch and ratio of No. of grains of primary branch to No. of grains of secondary branch. (3) Leaf length, leaf width, leaf basal angle, drooping angle of top three leaves and specific leaf weight from flag leaf to the 3rd leaf in all cultivars with PS were enhanced with decreasing planting density, and were higher than those in CK except for leaf basal angle and drooping angle. (4) With decreasing planting density, length of basal 1st, 2nd, and 3rd internodes were shortened, and culm diameter, culm wall thickness, dry matter weight per unit internode of basal inernodes, neck internode length, stalk length, plant height and gravity center height were increased. (5) The breaking resistance and bending moment of basal 1st, 2nd and 3rd internodes were increased with decreasing planting density, but lodging index was decreased. Therefore, for increasing yield with PS, the large panicle cultivar should reduce planting density appropriately, and increase grain number per panicle; the medium panicle cultivar should coordinate number of panicles and spikelets per panicle, getting a large amount of the total spikelets; the small panicle cultivar should depend on number of panicles. When the plant density reduced in PS, panicle traits and top three leaves area could be improved, but leaf basal angle and drooping angle could be increased; meanwhile, it was benefical to shorten the length of basal internodes and increase culm diameter, culm wall thickness and dry matter weight per unit internode, resulting in enhanced breaking resistance and reduced lodging index.