种植密度和施氮量对等行距机采棉根系形态指标及产量的影响

Effects of Nitrogen Fertilizer and Density on Dry Matter Accumulation,Root Growth and Yield of Cotton with Equal Row Spacing

【目的】研究不同种植密度和氮肥施用量对76 cm等行距机采棉根系形态指标及产量的影响。【方法】采用裂区设计,分别为主区密度(M_(1):22.5×10^(4)株/hm^(2)、M_(2):18×10^(4)株/hm^(2)、M_(3):13.5×10^(4)株/hm^(2))和副区氮肥(N_(1):0 kg/hm^(2)、N_(2):300 kg/hm^(2)、N_(3):600 kg/hm^(2)),分析不同种植密度和施氮量对机采棉根系各形态指标、产量及构成因素的影响。【结果】施氮量为N_(2)(300 kg/hm^(2))可使籽棉产量显著增加10.6%~14.5%。但施氮量过高(600 kg/hm^(2))时,干物质积累量会有所下降。适当提高种植密度和施氮量对棉花根重密度、根长密度、根表面积密度、根体积和根系平均直径等指标均有促进作用。最高处理M_(1)N_(2)(22.5×10^(4)株/hm^(2),300 kg/hm^(2))在根系质量和根体积分别比最低处理M_(3)N_(3)(13.5×10^(4)株/hm^(2),600 kg/hm^(2))高34.3%、50.1%,在根系平均直径和平均根表面积分别比最低处理M_(3)N_(2)(13.5×10^(4)株/hm^(2),300 kg/hm^(2))分别高36.1%、56.2%.根长密度在处理M_(1)N_(3)(22.5×10^(4)株/hm^(2),600 kg/hm^(2))下最大,比最低处理高M_(3)N_(2)20.8%。最佳高产组合为M_(2)N_(2)(18×10^(4)株/hm^(2),300 kg/hm^(2)),较最低组合M_(2)N_(3)(18×10^(4)株/hm^(2),600 kg/hm^(2))高18.5%。【结论】种植密度为18×10^(4)株/hm^(2),施氮量(纯氮)为600 kg/hm^(2),能促进新疆南疆地区76 cm等行距机采棉种植模式产量提升和形成良好的根系构型。

【Objective】To study the effects of different planting densities and nitrogen application amounts on the morphological index and yield of 76 cm equal-spaced cotton roots.【Method】The split-zone design was adopted,which was divided into the main zone density(M_(1):225,000 plants/hm^(2),M_(2):180,000 plants/hm^(2),M_(3):135,000 plants/hm^(2))and the sub-zone nitrogen fertilizer(N_(1):0 kg/hm^(2),N_(2):300 kg/hm^(2),N_(3):600 kg/hm^(2)).【Result】The results showed that the yield of seed cotton increased significantly by 10.6%-14.5%with nitrogen application rate of 300 kg/hm^(2).However,when the nitrogen application rate was too high(600 kg/hm^(2)),the dry matter accumulation would decrease.Appropriate increase of planting densities and nitrogen application rates could promote cotton root weight density,root length density,root surface area density,root volume and average root diameter.The root mass and root volume of the highest treatment M_(1)N_(2)(225,000 plants/hm^(2),300 kg/hm^(2))were 34.3%and 50.1%higher than those of the lowest treatment M_(3)N_(3)(135,000 plants/hm^(2),600 kg/hm^(2)),respectively,and the average root diameter and average root surface area were 36.1%and 56.2%higher than those of the lowest treatment M_(3)N_(3)(135,000 plants/hm^(2)·300kg/hm^(2)),respectively.The root length density was the highest under M_(1)N_(3)(225,000 plants/hm^(2),600 kg/hm^(2)),which was 20.8%higher than that under the lowest treatment.The final best combination with high yield was M_(2)M_(2)(180,000 plants/hm^(2),300 kg/hm^(2)),which was 18.5%higher than that of the lowest combination M_(2)N_(3)(180,000 plants/hm^(2),600 kg/hm^(2)).【Conclusion】It can be seen that the planting density of 180,000 plants/hm^(2)and the nitrogen application rate(pure nitrogen)of 600 kg/hm^(2)can promote the yield improvement and root formation in the machine-picked cotton planting mode with an equal row spacing of 76 cm in southern Xinjiang.