新疆机采棉花实现叶片快速脱落需要的温度条件

随着机采棉的快速推进,籽棉含杂率过高导致清理工序过多及纤维不必要的损伤。新疆棉区棉花生长后期的热量资源有限,如何合理喷施脱叶催熟剂是改善原棉品质的关键技术措施。本研究采用分期喷施脱叶催熟剂的方式,探讨了温度变化对棉花叶片脱落率的影响及实现棉花叶片快速脱落需要的温度条件。结果表明,在喷施脱叶催熟剂后(7.0±1.0)d内,棉花叶片脱落率最高,达55%～79%,且与最高温度和每日≥12°C有效积温呈显著的线性关系。若要在喷施脱叶催熟剂后(7.0±1.0)d内实现>55%的叶片脱落率,则应满足该时间段最高温度大于27.2°C、每日≥12°C有效积温大于7.0°C·日的要求。因此,喷施脱叶催熟剂后(7.0±1.0) d内是实现良好脱叶效果的关键时间段,期间的最高温度和每日≥12°C有效积温则是影响的关键因素。

Temperatures of promoting rapid leaf abscission of cotton in Xinjiang region

Machinical harvesters have increasing used in recent years, but excessive seed-cotton cleaning processes resulting from the higher foreign matter of mechanically harvested cotton cause unintended fiber damage. How to apply the defoliant to improve lint quality is a dominant cultural practice, because temperatures are unstable in the Xinjiang cotton belt with minimum dropping sharply in early autumn. The objective of this study was to analyze the relationship between temperatures and the rapid leaf abscission of cotton. The cotton leaf abscission rate was the highest, being from 55% to 79% at (7.0±1.0) days after defoliant application. And growing degree days (GDD) and maximum temperature were positively correlated with the cotton leaf abscission during (7.0±1.0) days after defoliant application. If obtaining more than 55% leaf abscission at (7.0±1.0) days after defoliant application, the maximum temperature and GDD should be more than 27.2°C and 7.0°C day, respectively. Therefore, the critical period promoting the good leaf abscission of cotton is during (7.0±1.0) days after defoliant application, and the dominant temperature factors influencing cotton leaf abscission are the maximum temperature and growing degree days.