Vol. 8, Issue 12, Part D (2024)

At the All India Coordinated Cotton Improvement Project, MPKV, Rahuri, Dist. Ahmednagar, Maharashtra, India, a field experiment study on the “Impact of canopy management practices on physiological and yield parameters of Bt Cotton (Gossypium hirsutum L) under high-density planting systems (HDPS)” was carried out during the Kharif season of 2022. Two factors, namely spacing viz.,S₁ (60x30 cm), S₂ (90x30 cm), S₃ (120x30 cm) and S₄ (120x60 cm) and canopy management practices viz., T₁ (Pruning at 40 DAS and topping at 70 DAS), T₂ (Pruning at 50 DAS and topping at 80 DAS), T₃ (Mepiquat chloride @ 50 ppm at 55 and 75 DAS) and T₄ (No pruning and no topping - control), were used to set up the experiment, which was replicated three times. 
The experiment was conducted using the RCH-659 Bt cotton hybrid seed. With the exception of 30 DAS, where only spacing had a significant effect, the results showed that the spacing and treatment (canopy management practices) at 60 and 90 DAS had a significant impact on physiological parameters, including the chlorophyll index (SPAD), rate of photosynthesis, leaf area index, and specific leaf weight. With treatment T₁ (pruning at 40 DAS and topping at 70 DAS) in 60 and 90 DAS, the spacing S4 (120x60 cm) had the significantly greatest chlorophyll index (SPAD), rate of photosynthesis, and specific leaf weight.
The maximum leaf area index was recorded by treatment T₁ (pruning at 40 DAS and topping at 70 DAS) with spacing S1 (60x30 cm), whereas the lowest leaf area index was obtained at both 60 and 90 DAS by treatment T₁ (pruning at 40 DAS and topping at 70 DAS) with spacing S4 (120x60 cm). When treated with T₁ (pruning at 40 DAS and topping at 70 DAS) under spacing S4 (120 x 60 cm), the yield parameters, including seed cotton yield plan T₁, demonstrated better results. Treatment T₁ (pruning at 40 DAS and topping at 70 DAS) with spacing S2 (90 x 30 cm) had the highest seed cotton yield ha^-1.