MOISTURE CONSERVATION AND OPTIMUM FERTILIZER LEVELS FOR BT COTTON (GOSSYPIUM HIRSUTUM L.) HYBRID UNDER RAINFED CONDITION

Abstract

A three-year investigation (2019-20 to 2021-22) was conducted at the Cotton Research Station, Nanded, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani (Maharashtra, India). The study aimed to evaluate the response of Bt cotton hybrids to moisture conservation practices and to optimize fertilizer levels in a rainfed environment. The experiment was arranged in a split-plot design with three replications. Four moisture conservation practices [M1 - Control i.e. flat bed, M2 - opening of every furrow at 60 DAS, M3 - application of super absorbent @ 12.5 kg ha-1 and M4 - broad bed and furrow] in main plot and four fertilizer levels [F1 - 80:40:40 NPK kg ha-1, F2 - 100:50:50 NPK kg ha-1, F3 - 120:60:60 NPK kg ha-1 and F4 - 140:70:70 NPK kg ha-1] were accessed in sub plots. Moisture conservation practices, broad bed and furrow (BBF) method and opening every furrow at 60 days after sowing (DAS) had improved several aspects of Bt-cotton growth. Specifically, these practices led to increased plant height, a greater number of monopodial and sympodial branches, and enhanced nutrient uptake compared to the control (flat bed). Sowing cotton on a broad bed and furrow (BBF) system and opening furrows at 60 days after sowing (DAS) significantly improved soil moisture content compared to flat bed sowing. This improved moisture retention led to an increase in yield-contributing characteristics, seed cotton yield, and lint yield of Bt cotton hybrid NHH 44. The highest harvest index was observed in the furrow-opening treatment. The BBF method resulted in the highest Gross Monetary Return (GMR) of ₹1,52,137 per hectare. However, the furrow-opening treatment proved to be the most profitable, yielding the highest Net Monetary Return (NMR) of ₹80,281 per hectare and the best Benefit-Cost (B:C) ratio of 2.15. These moisture conservation techniques did not affect the fiber properties of the Bt cotton. An NPK fertilizer application rate of 140:70:70 kg ha-1 resulted in superior growth compared to the lower rate of 80:40:40 kg ha-1. The 140:70:70 kg/ha NPK level significantly increased seed cotton yield (2330 kg ha-1), Gross Monetary Return (GMR) (₹1,54,707 ha-1), Net Monetary Return (NMR) (₹81,210 ha-1), and the Benefit-Cost (B:C) ratio (2.10) compared to the 100:50:50 kg ha-1 level. These results were comparable to the 120:60:60 kg ha-1 NPK level in terms of seed cotton yield and overall profitability. The harvest index increased with NPK levels up to 120:60:60 kg ha 1 , while the lint yield at this same level was significantly higher than the control group. Higher fertilizer levels also notably improved the uniformity index compared to the lowest application rate (F1). Furthermore, the overall uptake of nitrogen, phosphorus, and potassium by the crop increased significantly as the fertilizer level was raised.