Assessment of morpho-physiological and yield performance of Bt cotton under HDPS using diverse canopy management techniques

The investigation entitled “Assessment of morpho-physiological and yield performance of Bt cotton under HDPS using diverse canopy management techniques” was conducted using a split-plot design and replicated thrice during the Kharif 2023 season at the All India Coordinated Cotton Improvement Project, MPKV, Rahuri, Dist. Ahilyanagar (M.S.), India. The experiment utilized the RCH-659 Bt cotton hybrid. The experimental field was arranged in 48-unit plots, each measuring approximately 6.30 x 6.00 m² for gross plot size, with net plot sizes varying according to spacing. Two factors were considered: spacing, viz., S1 (60x30 cm), S2 (90x30 cm), S3 (120x30 cm) and S4 (120x60 cm) and canopy management techniques 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. Morphological observations, such as minimum plant height and maximum sympodial length, were recorded in treatment T1 (pruning at 40 DAS and topping at 70 DAS) under spacing S4 (120 x 60 cm) compared to all other treatments and spacings. The maximum number of sympodia plant-1 was observed in T3 (Mepiquat chloride at 50 ppm at 55 and 75 DAS) under spacing S4 (120 x 60 cm) at harvest. Physiological parameters such as chlorophyll index (SPAD) and rate of photosynthesis were recorded superior results under treatment T1 (pruning at 40 DAS and topping at 70 DAS) with spacing S4 (120 x 60 cm) at 30, 60 and 90 DAS. Yield parameters such as seed cotton yield plant-1 showed superior results with treatment T1 (pruning at 40 DAS and topping at 70 DAS) under spacing S4 (120 x 60 cm). The significantly highest seed cotton yield ha-1 at 140 and 165 DAS and total seed cotton yield ha-1 was recorded in treatment T1 (pruning at 40 DAS and topping at 70 DAS) with spacing S2 (90 x 30 cm).