Effects of supplemental irrigation and soil fertilization on pearl millet under drought

Pearl millet was grown under rainfed (188 mm precipitation with an early and a terminal drought) or with one supplemental irrigation (63 mm during the early drought at 10 days after sowing) and with (80 kg N, 18 kg P, and 17 kg K ha-1) or without application of fertilizers. Improvement of soil fertility increased the dry matter and grain yield, water use efficiency, mining of soil water, concentrations of some leaf metabolites (soluble protein, free amino acids, total chlorophyll, and starch), and the activity of nitrate reductase, despite larger declines of psi(plant) and relative turgidity as compared to unfertilized plants under both the rainfed and irrigated conditions. Fertilizer-induced effects on soil water extraction, crop performance, and metabolism were higher under the irrigated as compared to the rainfed condition. Irrigation and soil fertilization showed an additive favorable effect, possibly because of their similarity of action on different plant processes, notwithstanding their differential effects on the plant water status.