Assessing the impact of topping timing on cotton development, Yield components and fibre quality · Electronic Theses and Dissertations

Author: Mandivanzira, Caleb N.
Title: Assessing the impact of topping timing on cotton development, Yield components and fibre quality
Abstract: Despite the widespread adoption of cotton production in Zimbabwe limited research has been
carried out on how the timing of topping influences both yield and fibre quality under local field
conditions. Most previous studies have emphasised general agronomic practices leaving a gap in
understanding the optical topping period for maximum productivity. Addressing the gap is
critical for providing farmers with evidence based recommendations suited to Zimbabwean
growing environments. The field study was done at Conrise Farm, Rafingora, Zimbabwe during
the 2024-2025 growing season to assess the impact of topping timing on cotton growth, yield
components and fibre quality. The study was laid out in a randomized complete block design
(RCBD) with four treatments namely no topping as the control, early topping (eight weeks after
emergence), medium topping (12 weeks), and late topping (16 weeks). The study revealed
significant treatment effects on plant height from 8 weeks after planting (p=0.021) to 24 weeks
after planting (p<0.001), bolls per plant (p<0.001) and days to boll splitting (p<0.001). No
topping had the highest number of bolls (12), while early topping resulted in significantly fewer
number of bolls (7.62). Early topping accelerated the time to boll splitting (128.67 days)
compared to late topping which had 138.67 days. Seeds per boll showed no significant
differences among the different treatments (p=0.58) having an average of 15.7 across treatments.
Fibre quality parameters such as micronaire (p=0.501) and upper half mean length (p=0.264)
were not statistically significant. The study concluded that while topping timing significantly
affects cotton development and some yield components, fibre quality remains relatively stable
across different topping regimes. It was recommended that mid to late topping be done so as not
to compromise yield.
Date: June 2025
Publisher: BUSE
Keywords: Cotton production; Cotton development
Supervisor: Mr J.C. Chitamba

Item sets: Department of Crop Sciences

Media: Mandivanzira - Crop.pdf