Density and row spacing of short-season cotton suitable for machine picking in the cotton region of Yellow River Basin.

To determine the suitable planting density and row spacing of short-season cotton suitable for machine picking in the Yellow River Basin of China, we conducted a two-year field experiment in Dezhou during 2018-2019. The experiment followed a split-plot design, with planting density (82500 plants·hm-2 and 112500 plants·hm-2) as the main plots and row spacing (equal row spacing of 76 cm, wide-narrow row spacing of 66 cm+10 cm, equal row spacing of 60 cm) as the subplots. We examined the effects of planting density and row spacing on growth and development, canopy structure, seed cotton yield and fiber quality of short-season cotton. The results showed that plant height and LAI under high density treatment were significantly greater than those under low density treatment. The transmittance of the bottom layer was significantly lower than under low density treatment. Plant height under 76 cm equal row spacing was significantly higher than that under 60 cm equal row spacing, while that under wide-narrow row spacing (66 cm +10 cm) was significantly smaller than that under 60 cm equal row spacing in peak bolling stage. The effects of row spacing on LAI varied between the two years, densities, and growth stages. On the whole, the LAI under the wide-narrow row spacing (66 cm+10 cm) was higher, with the curve declining gently after the peak, and it was higher than that in the two cases of equal row spacing in the harvest time. The change in transmittance of the bottom layer presented the opposite trend. Density, row spacing, and their interaction had significant effects on seed cotton yield and its components. In both years, seed cotton yield was the highest (3832 kg·hm-2 in 2018, 3235 kg·hm-2 in 2019) under wide-narrow row spacing (66 cm+10 cm), and it was more stable at high densities. Fiber quality was less affected by density and row spacing. To sum up, the optimal density and row spacing of short-season cotton were as follows: density with 112500 plants·hm-2 and wide-narrow row spacing (66 cm+10 cm).为确定黄河流域短季棉适宜机采的种植密度和行距配置,于2018—2019年在德州市科技园进行田间试验,采用裂区设计,以种植密度(低密度8.25万株·hm-2和高密度11.25万株·hm-2)为主区,行距配置(76 cm等行距、宽窄行66 cm+10 cm和60 cm等行距)为裂区,探讨了不同密度和行距配置对短季棉生长发育、冠层结构和籽棉产量及纤维品质的影响。结果表明: 盛铃期高密度处理的株高和叶面积指数(LAI)显著高于低密度,底层透光率显著低于低密度。76 cm等行距的株高显著高于60 cm等行距,宽窄行(66 cm+10 cm)的株高显著低于60 cm等行距;行距对LAI的影响在不同年份、密度及生育时期间存在差异,总体宽窄行(66 cm+10 cm)的LAI较高,且峰值后曲线下降平缓,在收获期高于两个等行距;底层透光率变化与LAI呈相反的规律。密度和行距配置及两者互作对籽棉产量及产量构成均有显著影响,两年均为宽窄行(66 cm+10 cm)产量最高(2018和2019年为3832和3235 kg·hm-2),且高密度下宽窄行(66 cm+10 cm)产量更稳定。密度和行距配置对棉花纤维品质影响较小。综上,短季棉的最佳密度和行距配置模式为:11.25万株·hm-2,宽窄行(66 cm+10 cm)。.