Abstract:

In order to clarify the sensitive response of different main cotton varieties to chemical topping agents in Bayingol Mongolian Autonomous Prefecture of Xinjiang, four local main cotton varieties were selected as the research objects to study and analyze the effects of DPC (25% slow-release emulsion in water) treatment with chemical topping agents on plant height, LAI, aboveground biomass accumulation, yield and quality of different cotton varieties. The results showed that 30 days after topping, the plant height of different cotton varieties was significantly higher than that of artificial topping by 4.09%-7.54% (P<0.05), among which ‘Ba 43541’ increased the least. LAI of different cotton varieties under two topping methods ranged from 2.96 to 4.03. Compared with before topping, LAI of cotton variety ‘Ba 43541’ increased the most under chemical topping method. The changes of leaves, stems, buds and total dry matter mass of different cotton varieties under two topping methods were different, but the changes of dry matter mass under two topping methods were not significant (P>0.05). Compared with manual topping, chemical topping had little effect on fiber length, uniformity, specific strength, micronaire value and elongation of different cotton varieties, and the difference was significant. Compared with manual topping, the yield of seed cotton of different cotton varieties increased by 0.35%-2.49% under chemical topping, among which the yield of cotton variety ‘Ba 43541’ was the highest, with 163.15 kg/hm², followed by ‘Xinluzhong 71’, ‘Xinluzhong 78’ and ‘Xinluzhong 81’. ‘Ba 43541’, the main cotton variety in Bayingol, is the most sensitive to chemical topping agent, and has the best effect of chemical capping, and has the potential to increase production.

Key words: chemical topping, Bayingol area, cotton, main varieties, response mechanism, yield, quality