Foliar Potassium Nitrate for Yield Enhancement and Terminal Heat Stress Mitigation in Wheat under Farmer Field Conditions in Punjab

Potassium Nitrate Application Enhances Wheat Yield under On-Farm Conditions

Abstract

A field survey followed by farmer-participatory field experiments was conducted in Fatehgarh Sahib and Kapurthala districts of Punjab, India, to evaluate the adoption pattern and agronomic benefits of foliar potassium nitrate (KNO₃) application in wheat cultivar PBW826 under terminal heat stress conditions. The survey of 90 farmers (45 from each district) revealed that KNO₃ adoption was 42.2% in Fatehgarh Sahib and 33.3% in Kapurthala. Among adopters, the 2.0% KNO₃ concentration was the most commonly used in both districts (22.2%), followed by 1.0% and 1.5% concentrations. Two foliar sprays were preferred over a single spray, indicating farmers’ inclination towards repeated applications. Farmers primarily perceived KNO₃ as a heat-stress mitigation input, while a considerable proportion also reported yield improvement as a major benefit. Based on the survey findings, farmer-participatory field experiments were conducted in 10 farmer fields in each district, comprising three treatments: control, 1% KNO₃, and 2% KNO₃ applied at the booting and anthesis stages. Foliar application of 2% KNO₃ significantly improved growth and yield attributes in both districts. In Fatehgarh Sahib, the treatment recorded the highest plant height (98.6 cm), effective tillers (406 m–2), 1000-grain weight (42.47 g), grain yield (5.87 tonnes ha–1), and straw yield (8.72 tonnes ha–1), while corresponding values in Kapurthala were 100.3 cm, 407 m–2, 42.90 g, 6.01 tonnes ha–1, and 9.19 tonnes ha–1, respectively. Economic analysis also showed maximum profitability under the 2% KNO3 treatment, with gross returns of Rs. 1,42,288 and Rs. 1,45,683 acre–1 and net returns of Rs. 94,985 and Rs. 98,505 acre–1 in Fatehgarh Sahib and Kapurthala, respectively. The study demonstrated that foliar application of potassium nitrate @ 2% at critical growth stages is an effective and economically viable strategy for enhancing wheat productivity and mitigating the adverse effects of terminal heat stress under farmer field conditions.