Dry matter partitioning in Bt and non Bt cotton (Gossypium hirsutum) cultivars under different sowing environments of Punjab

A field experiment was conducted at Punjab Agricultural University (PAU), Regional Research Station (RRS), Faridkot and Bathinda during rainy (kharif) season 2017 to evaluate the performance of Bt and non Bt cotton (Gossypium hirsutum L.) cultivars under different sowing environments. The experiment was laid out in split plot design with 3 sowing dates (April 20, May 10 and May 30) in main plots and 4 American cotton cultivars [2 Bt cultivars (NCS 855 BGII and RCH 650 BGII) and 2 non Bt cultivars (F 2228 and F 1861)] in sub-plots. Results of the pooled data indicated that early sown (April 20) crop accumulated more dry matter production, higher crop growth rate (CGR) as well as relative growth rate (RGR) followed by crop sown on May 10 and May 30. Maximum CGR (14.35–15.48 g/m2/day) was obtained during 90–120 DAS (days after sowing) while RGR was highest during 60–90 DAS. Among tested cultivars, F 1861 exhibited better CGR and RGR values and hence, accumulated higher dry matter (1303.0 g/m2) followed by F 2228 (1276.9 g/m2), NCS 855 BGII (1261.1 g/m2) and RCH 650 BGII (1206.7 g/m2). Dry matter accumulation in fruiting bodies has started around 90 DAS and accounted for 30–35% of total above ground biomass. Bt cultivar NCS 855 BGII, accumulated higher dry matter in fruiting bodies (458.1 g/m2), though at par with RCH 650 BGII (432.2 g/m2) but, significantly higher than F 1861 (403.3 g/m2) and F 2228 (401.9 g/m2). Dry matter accumulation towards fruiting bodies in Bt cultivars was ~9% higher than non Bt cultivars which may be prime reason for better yield performance of Bt cotton.