Enhancing drought resilience in pearl millet (Pennisetum glaucum L.) through nano foliar nutrient and biostimulant interventions

Pearl millet ( Pennisetum glaucum L.) is an important cereal crop in rainfed regions owing to its inherent drought tolerance. However, drought stress adversely affects crop growth, physiological processes and yield. A pot experiment was conducted during the post-monsoon season at ICAR–Central Research Institute for Dryland Agriculture (ICAR-CRIDA), Hyderabad to evaluate the effects of different nano-nutrient foliar sprays on pearl millet under deficit moisture stress. Foliar application of nano-nutrients during and after stress alleviation at the vegetative and flowering stages improved crop growth and yield attributes. Compared with the control, yield losses were limited to 9% and 13% following application of SWAS @ 0.5% after alleviation of vegetative-stage stress and to 13% following application of NDAPAS @ 0.2% after alleviation of flowering-stage stress. At the vegetative stage, foliar application of SWAS at 0.5% resulted in the highest relative water content (RLWC, 93.2%), soil moisture (19.3%), membrane stability index (MSI, 93.2%) and nitrate reductase (NR) activity (2962.2 µg g⁻ 1 FW) while maintaining lower levels of proline (32.0 µg g⁻ 1 FW), malondialdehyde (MDA, 15.7 µg g⁻ 1 FW), free amino acids (FAA, 21.2 µg g⁻ 1 FW) and total soluble sugars (TSS, 1.8 µg g⁻ 1 FW). At the flowering stage, NDAPAS at 0.2% resulted in the highest RLWC (93.0%) and soil moisture (17.9%), with reduced proline (33.0 µg g⁻ 1 FW), FAA (2.1 µg g⁻ 1 FW), and TSS (22.8 µg g⁻ 1 FW). Foliar sprays also improved chlorophyll fluorescence parameters (φP₀, φE₀, ψ₀, δR₀, and performance index) showing better photosynthetic efficiency and stability of photosystem II under stress. Application of SWAS at 0.5% at the vegetative stage and NDAPAS at 0.2% at the flowering stage was the most effective for improving crop yields under deficit moisture stress.