Assessing the Resilience of Diverse Millet Species under Nitrogen and Moisture Co-limited Conditions

Crop yields are highly susceptible to various abiotic stresses, which are expected to intensify under global climate change. Millets are recognized as potential candidates to enhance food and nutritional security for a growing global population under a changing climate. Nitrogen (N) deficiency and drought are among the leading abiotic stresses affecting crop production. This study aimed to explore the growth, reproductive biomass, N uptake, and N use efficiency of three millet species under N-deficient and drought conditions. In a pot experiment, one variety of each of finger millet (Eleusine coracana L. Gaertn), proso millet (Panicum miliaceum L.), and foxtail millet (Setaria italica L.) were cultivated under two moisture regimes (80% field capacity as well-watered and 40% field capacity as drought treatment) coupled with two N levels (no N application and recommended N application by the Department of Agriculture, Sri Lanka). Across all four treatment combinations, proso millet had significantly lower tissue N concentration in roots, shoots, and panicles compared to finger millet and foxtail millets. Finger millet demonstrated a significant increase in root dry weight and root mass ratio across all four treatments compared to the other two millets. In a given N treatment, each millet species produced similar panicle dry weights regardless of the two moisture regimes, indicating their greater ability in biomass allocation to reproductive structure. However, N-deficient conditions significantly reduced panicle biomass in finger and foxtail millets, whereas proso millet maintained similar panicle dry weights across two N levels, demonstrating its ability to withstand N-deficit conditions. The study confirms that all three varieties of millet species can perform better under moisture-limited conditions, with proso millet variety being well-adapted to environments where moisture and N limitations co-exist.