密度与氮肥对机采棉叶铃分布的影响及与产量的关系

为研究种植密度与施氮量对机采棉冠层叶面积指数、透光率和果枝长度等的影响,采用裂区试验设计,主区设2个种植密度D18(18万株/hm~2)和D24(24万株/hm~2),副区设4个施氮量N0(0kg/hm~2)、N170(170kg/hm~2)、N320(320kg/hm~2)和N470(470kg/hm~2)。结果表明,同一施氮量下,随种植密度增大,单株结铃数、单铃重与衣分减小,冠层上、中和下部叶面积指数增大,冠层上、中和下部果枝长度呈先降后增的趋势,冠层开度降低,冠层上、中和下部单铃重逐渐降低。同一种植密度下,当种植密度为D18时,随施氮量的增加,单株结铃数、单铃重、衣分、籽棉产量、皮棉产量、DIFN、冠层上、中和下部叶面积指数及果枝长度均呈上升趋势,表现为N470N320N170N0,种植密度D24条件下呈先升后降的趋势,表现为N320N470N170N0。D24N320处理虽然较最高籽棉产量略低,但差异不显著,其增产率及氮肥农学利用效率最高,在减少氮肥投入量的同时也减轻了由此产生的环境污染。因此,当种植密度为24万株/hm~2、施氮量为320kg/hm~2是本试验条件下最理想的种植密度与施氮量。

Effect of planting density and nitrogen application on the distribution of leaf and boll in machine picking cotton and its relationship with yield

The aim of this study was to investigate the effect of planting density and nitrogen application on machine picking cotton canopy LAI transmittance and branch length index, using split plot design. The main area of 2 D18 planting density (180 thousand plants/hm²), D24 (240 thousand plant/hm²), deputy district with 4 nitrogen N0 (0 kg/hm²), N170 (170 kg/hm²), N320 (320 kg/hm²) and N470 (470 kg/hm²) were designed. The results showed that:Under the same nitrogen application amount, the boll number and boll weight, lint percentage decreased, canopy, canopy LAI increased with the increasing of planting density, and the branch length increased after the first dropping trend, DIFN decreased, boll, lower canopy weight gradually reduced. Under the same D18 planting density of condition, with the increase of nitrogen application amount, the boll number, boll weight and lint percentage, seed yield, canopy, LAI, branch length and DIFN increased, the performance of the N470 > N320 > N170 > N0. The planting density under the condition of D24 was increased after the first dropping trend, the performance was N320 > N470 > N170 > N0. The highest yield was the D18N470 treatment and followed by D24N320 treatment, and there was no significant difference between these two treatments. Although, the yield of D24N320 is 1.09% less than the D18N470, the amount of urea input (per hectare) 31.91% resulting in slightly lower yield, but caused lower the environmental harm. Therefore, when the planting density was 240 thousand/hm² and the amount of nitrogen was 320 kg/hm² were the optimum planting density and nitrogen application rate under the mode of machine harvest cotton planting in Southern Xinjiang.