Detopping reduces field duration of cotton while increases the yield and quality of cotton fiber

Abstract

Detopping is a management technique often used in cotton cultivation in various countries to maintain good architecture of the plants, which enables them to get better sunlight. Detopping also increases picking efficiency in cotton as crop maturity advances. Two field experiments were conducted at Cotton Research Farm, Gazipur, Bangladesh-one in 2018 and the other in 2019. The 1st experiment was conducted in 2018 using RCB design including five genotypes (BC-0479, BC-0495, BC-0514, JA-13/R and CB-12) and four detopping practices (no detopping, detopping at 80, 90 and 100 days after sowing, DAS) with three replications. In the 2nd experiment in 2019, performance of best three genotypes (BC-0479, BC-0495 and BC-0514 as obtained from the 1st study) was evaluated under three sowing dates (5, 15 and 25 July) and three detopping practices (detopping at 85, 90 and 95 DAS). The experiment used split-split-plot design where sowing dates were assigned in main plots, detopping in sub-plots and genotypes in sub-sub plots. In the experiment in 2018, the genotype BC-0479 produced highest seed cotton (3.90 t ha−1) and yielded 16 % more when detopping was done at 90 DAS as compared to no detopping. In 2019, the same genotype (BC-0479) yielded 5 % and 8 % higher when detopping was done at 85 DAS as compared to detopping at 90 and 95 DAS, respectively. In addition, this genotype matured 17 days earlier under detopping at 90 DAS as compared to no detopping in 2018, and 5 and 8 days earlier under detopping at 85 DAS as compared to 90 and 95 DAS in 2019 respectively. Genotype-wise maturity in BC-0479 in the year 2018 was found 21, 22, 18 and 23 days earlier than BC-0495, BC-0514, JA-13/R and CB-12, respectively. In the year 2019, the maturity of BC-0479 was 10 and 17 days earlier over BC-0495 and BC-0514, respectively. On the other hand, BC-0479 showed 3 %, 8 %, 13 % and 25 % higher yield than BC-0495, BC-0514, JA-13/R and CB-12, respectively in the year 2018, and 7 % and 12 % higher yield than BC-0495 and BC-0514, respectively in the year 2019. Fiber quality in terms of staple length, strength, uniformity index and micronaire was also improved by detopping practices irrespective of genotypes. Based on the results of the study detopping is suggested as a beneficial practice by increasing yield and quality of cotton fiber while shortening the field duration of cotton.

Keywords

• Cotton (Gossypium hirsutum L.)
• Detopping
• Field duration
• Lint quality
• Yield