棉花脱叶催熟剂对纤维品质的影响及应用时间的确定

棉花脱叶催熟技术是实现棉花机械采收的重要前提,确定脱叶催熟剂喷施时期及标准对实现良好的脱叶和催熟效果至关重要。本研究采用分期喷施脱叶催熟剂的方式,探讨了脱叶催熟剂对纤维品质的损伤程度,及与棉铃铃期之间的定量关系。结果表明,脱叶催熟剂对纤维长度的影响在品种间存在差异, 46%～69%的供试品种纤维长度较对照下降或持平,另有31%～54%的品种纤维长度反而较对照增加,所有品种纤维长度较对照平均仅降低0.2%～1.2%。纤维比强度受脱叶催熟剂的影响较为明显,其损伤量(处理与对照的差值)集中分布在-4～0 cN tex^-1之间。脱叶催熟剂对纤维比强度的损伤程度与喷施时间有关,铃龄30 d时喷施损伤大,铃龄37 d时喷施损伤减小,且有61%供试品种的比强度较对照平均增加了1.1cN/tex。脱叶催熟剂对纤维比强度的损伤量随棉铃铃期延长而加剧,因此可根据"脱叶催熟剂喷施时棉铃的铃龄与铃期的比值(Rd/b)"这一指标确定脱叶催熟剂的喷施时间。此外,棉铃铃期与棉铃体积、棉铃体积与纤维比强度均呈显著正相关关系。如要生产比强度>31 cN tex-1的棉花纤维,所选品种的棉铃体...

A method of defoliant application based on fiber damage and boll growth period of machine-harvested cotton

Defoliation technology is an essential prerequisite for machine-harvested cotton, and to apply defoliant to achieve better defoliation and improve fiber quality is an important method. The objective of this study was to analyze the quantitative relationship between fiber damage amount and boll growth period by defoliant. The results showed that defoliant had not significantly an effect on fiber length, which showed that all reduced by from 0.2% to 1.2% compared with the control, 46%-69% cotton varieties decreased or equal, whereas 31%-54% cotton varieties increased in fiber length compared with control. Fiber strength was affected significantly by defoliation, and the amplitude of fiber damage was concentrated between -4 cN tex^-1 and 0 cN tex^-1. The amount of fiber damage by defoliant was correlated to the spraying time in cotton boll growth, and the high damage at 30 days, whereas the lowest damage at 37 days. More than 61% cotton varieties showed an increased by average 1.1 cN tex^-1 on fiber strength compared with the control. Fiber strength damage because of defoliant increased with the increasing boll growth period. It was an indicator for determining the time of spraying defoliation based on the boll growth period and fiber damage (R_d/b) on fiber strength. Furthermore, cotton boll growth period and boll volume. Fiber strength and boll volume, boll volume and boll growth period, both showed significant positive correlation. If fiber strength of more than 31 cN tex^-1was produced in field, a cotton cultivar should be selected with boll volume of more than 31.8 cm³, boll growth period of more than 60.0 d and R_d/b more than 0.68. Defoliant used after 40.9 post-anthesis days could ensure fiber strength of less than 0.5 cN tex^-1.