不同冠层结构对棉田小气候及蕾铃脱落和产量的影响

为探讨黄河流域不同冠层结构下棉花产量及田间微环境差异,对去叶枝(T1)、去叶枝高矮相间(T2)、留叶枝(T3)、留叶枝高矮相间(T4)4个群体结构下棉花的产量和微环境进行研究。结果表明:冀棉958和农大棉601的留叶枝群体在各时期的底部透光率均显著降低,而T4群体底部透光率显著高于T3群体;各时期CO_2浓度与温度、湿度均成显著偏相关关系,花铃期高矮相间群体下层的CO_2浓度平均比空气中提高8.69%~11.63%,而中层CO_2浓度降低1.66%~4.24%。T4群体冠层内的温度显著降低,棉花群体下层的湿度和CO_2浓度显著提高;去叶枝群体脱落率较低,籽棉产量显著高于留叶枝群体;高矮相间群体籽棉产量高于常规群体;冀棉958和农大棉601的T4群体籽棉产量比T3群体分别提高15.79%和10.81%。因此,留叶枝群体采用高矮相间冠层明显改善棉田中下层微环境,降低脱落率,提高铃数,有利于形成产量。

Effects of Different Canopy Structures on Boll Abscission,Yield, and Field Microclimate of Cotton

To consider the difference of cotton yield and the field micro-environment under different canopy structures in the Yellow River basin, we studied cotton strains Jimian 958 and Nongdamian 601 under four different canopy structures. Different canopy structures were created through vegetative branch removal (T1, regular group), high (tow rows) and low (tow rows) plant-alternated vegetative branch removal (T2, irregular group), vegetative branch retention (T3, regular group), and high (tow rows) and low (tow rows) plant-alternated vegetative branch retention (T4, irregular group). The results showed that the light transmittances at the bottom of canopy in vegetable branch retention groups were significantly reduced in Jimian 958 and Nongdamian 601; however, the light transmittance at the bottom of the T4 group was significantly higher than that of the T3 group. The CO₂ concentration has significant partial correlations with temperature and humidity in each stage. During the flowering and blooming stage, compared with CO₂ concentration in the air, the CO₂ concentration in the down layer of high and low plant-alternated group on average increased 8.69%―11.63%, and that in the middle layer reduced by 1.66%―4.24%. The within-canopy temperature decreased significantly in the T4 group, and the cotton group down-layer humidity and CO₂ concentration increased significantly. The vegetative branch removal groups have a low abscission rate, and their seed cotton yields were significantly higher than those of the vegetation-retention groups. The seed cotton yields of the high and low plant-alternated groups were higher than the regular groups, especially the T4 groups of different varieties (Jimian 958 and Nongdamian 601) in which seed cotton yields increased by 15.79%, 10.81% higher than in the T3 group, respectively. Therefore, the vegetative branch retention group combined with high and low plant-alternated planting (T4) can improve thecotton lower-middle-class microclimate, reduce the abscission rate, and increase the number of bolls per unit area, which is helpful to increase production.