Effect of moisture conservation techniques on productivity, water-use efficiency and economics of Bt cotton (Gossypium hirsutum) in southern Rajasthan

A field experiment was conducted during 2 consecutive kharif seasons of 2014 and 2015 at Banswara, Rajasthan to assess the effect of moisture conservation techniques like, polymulching and drip irrigation on pro-ductivity, water-use efficiency and economics of Bt. cotton (Gossypium hirsutum L.) in sourthern Rajasthan. The experiment was laid out in randomized block design with 3 replications comprising eight treatment combinations. The results revealed that polymulching improved the growth, yield, nutrient uptake and water-use efficiency compared to conventional irrigation. Polymulching increased seed-cotton yield and water-use efficiency by 42.5 and 99% respectively in comparison to conventional irrigation. Drip irrigation with polymulching was significantly superior to drip irrigation without polymulching at all irrigation regimes. Water-use efficiency was observed the highest (93.6 kg/ha-cm) under drip irrigation at 0.6 ETc + polymulching, while the lowest (28 kg/ha-cm) was recorded under conventional irrigation. The uptake of NPK was significantly influenced by polymulching and drip irrigation (with and without polymulching) compared to conventional irrigation. The maximum seed cotton yield (5, 504 kg/ha), gross returns (220, 145/ha) and net returns (169, 105/ha) were recorded under drip irrigation at 0.8 ETc + polymulching, which was at par with drip irrigation at 0.6 ETc + polymulching and significantly superior to rest of the treatments. Maximum B: C ratio (3.31) was also recorded under drip irrigation 0.8 ETc + polymulching, which remained at par with drip irrigation at 0.6 ETc + polymulching, drip at 0.8 ETc without mulching and polymulching in conventional irrigation. Drip irrigation at 0.6 ETc with polymulching can be recommended as best moisture conservation technology for enhancing productivity of Bt. cotton under the agro-climatic condition of southern Rajasthan.