Abstract:

To address issues related to reduced growth rate, shifting center of gravity, and nutritional loss after cotton topping, this study examines the effects of ‘Xinluzao No.62’ on morphological and yield indicators under chemical and traditional manual topping methods. The goal is to elucidate cotton’s growth response to different topping techniques. Thirty cotton plants were subjected to chemical and manual topping treatments, with measurements being taken at specific intervals (0, 7, 15, and 30 days after topping) for plant height, number of fruit branches, and number of bolls per plant. Additionally, prior to leaf defoliation agent application, the number of seeded and unseeded bolls was recorded to determine the boll setting rate. Each treatment aimed to assess cotton harvest density, average single-plant bell weight, single-bell weight, and lint percentage, with subsequent calculation of seed cotton and lint yield. Results indicated that chemical topping of cotton led to a significant increase in plant height and fruit branches within 30 days compared to artificial topping. The number of large and small bells decreased initially (0-15 days) after topping but increased after 30 days. Parameters such as flocculation rate, single bell weight, lint percentage, and yield decreased, while the number of single bells increased. Ultimately, manual topping resulted in slightly higher yields than chemical topping, with no discernible difference between treatments. It is advisable to employ artificial topping in cotton fields with robust cotton, substantial plant biomass, and late topping to expedite the transition from vegetative to reproductive growth, fostering trellis development. Conversely, for fields with weak cotton growth, chemical topping is recommended to balance nutrition and reproductive growth, achieve topping effects, prevent mechanical damage from artificial topping, and maximize cotton’s production potential.

Key words: cotton, chemical topping, manual topping, morphological index, boll opening rate, yield, principal component analysis