Soil water stress and nitrogen deficiency are major constraints to onion productivity and resource‐use efficiency in the Indo‐Gangetic plains. A two‐year field experiment (2016–17 and 2017–18) evaluated the combined effects of three microsprinkler irrigation regimes (0.6, 0.9, and 1.2 ETc) and four nitrogen levels (0%, 75%, 100%, and 120% of the recommended dose) on growth, physiological traits, bulb yield, and water and nitrogen use efficiencies of winter onion. Increasing irrigation and nitrogen significantly enhanced plant growth, leaf water status, chlorophyl content, nitrate reductase activity, and bulb yield. The highest yield was obtained under 1.2 ETc with 100% nitrogen (96 kg N ha −1 ), reflecting optimal water–nutrient availability and improved physiological performance. Water and nitrogen stress increased proline accumulation, antioxidant enzyme activity, and lipid peroxidation, resulting in yield reduction. Water use efficiency was maximized under mild deficit irrigation (0.9 ETc) with higher nitrogen, whereas nitrogen use efficiency was highest under high irrigation with moderate nitrogen supply. The results indicate that integrating microsprinkler irrigation with balanced nitrogen fertilization can enhance onion productivity and resource‐use efficiency. Under water‐limited conditions, irrigation at 0.9 ETc with adequate nitrogen provides a practical and sustainable management option.
Banik et al. (Sun,) studied this question.