Effect of irrigation scheduling and different levels of zinc and boron on yield, economics, water productivity and nutrient uptake in aerobic rice (Oryza sativa)

A field study was conducted during the rainy (kharif) seasons of 2015 and 2016 at Chiplima, Sambalpur, under west central tableland zone of Odisha, to evaluate 6 different micronutrient combinations under 4 different irrigation schedules in aerobic rice (Oryza sativa L.). Application of irrigation after 3 rainless days resulted in significantly highest grain yield (4.05 t/ha) over all other treatments owing to optimum soil moisture and nutrient availability. The highest number of panicle bearing tillers/m² (375.1), panicle length, filled grains/panicle (108.5) and 1,000-grain weight (26.23 g) attributed to the higher yield under this treatment. It also resulted in the highest net returns (30,316/ha), benefit: cost (B:C) ratio of 1.88 and nutrient uptake. Among different levels of micronutrient, an application of recommended dose of fertilizer (RDF, 80-40-40) kg/ha N, P₂O₅ - K₂O + 5 kg Zn/ha + 0.2% B as foliar spray (2 sprays) registered significantly highest grain yield of 4.24 t/ha along with higher values of yield attributes such as panicle-bearing tillers/m² (391.1), panicle length (25.52 cm), filled grains/panicle (117.9) and 1,000-grain weight (26.17 g). It also resulted in higher net return (30,362/ha), benefit: cost ratio of 1.89 and nutrient uptake than all the other treatments. Water use was highest in case of irrigation scheduling after 3 rainless days (91.33 cm) with lowest water productivity (0.43 kg/m³). Out of 6 micronutrient levels, application of RDF (8040–40 N, P₂O₅ and K₂O Kg/ha) + 5 kg Zn/ha + 0.2% B as foliar spray (2 sprays) resulted in the highest water productivity (0.57 kg/m³) owing to higher yield and low water use. However, the interaction effect was statistically nonsignificant.