Mitigation of Terminal Heat Stress in Aerobic Rice (Oryza sativa L.) by Nitrogen and Potassium Application

Heat stress is one of the major environmental stresses limiting rice productivity. Selecting heat-tolerant rice cultivars and implementing proper nutrient management techniques could result in a high and consistent yield.

Field experiments were conducted at the Kerala Agricultural University, Thrissur, during the summer (2020 and 2021) to study the response of different rice varieties to elevated temperatures (2 to 3°C) during the flowering to maturity stage, with different N and K levels under aerobic conditions. The experimental treatments comprised of V₁F₀ - Vaishak + 60 kg N and 30 kg K₂O (control), V₁F₁ - Vaishak + 60 kg N and 30 kg K₂O under stress, V₁F₂ - Vaishak + 90 kg N and 45 kg K₂O under stress, V₁F₃ - Vaishak + 120 kg N and 60 kg K₂O under stress, V₂F₀ - Aiswarya + 60 kg N and 30 kg K₂O (control), V₂F₁ Aiswarya + 60 kg N and 30 kg K₂O under stress, V₂F₂- Aiswarya+90 kg N and 45 kg K₂O under stress, V₂F₃- Aiswarya+120 kg N and 60 kg K₂O under stress. These were laid out in a randomized complete block design and replicated three times.

The study revealed that the highest yield (2909 and 2456 kg/ha) and nutrient uptake were observed with application of 120 kg N and 60 kg K₂O from Vaishak. The treatments V₁F₃ and V₂F₃ showed higher NPK uptake than the recommended fertilizer dose in both seasons.