Contrasting patterns in growth attributes, root traits plasticity, and defence mechanism of maize under deficit moisture and phosphorus supply

Abstract Background: The phosphorus uptake in plants is decreased due to soil water deficiency which negatively affects plant growth. How the interaction of soil moisture and P deficiency affects the morpho-physiological and biochemical responses of plants is still little known. Methods: This study investigates physiological and biochemical responses of maize hybrids under interaction of moisture and P deficit conditions. Three levels of water (well-watered, moderate drought, severe drought) and P-supply (P100, P50, and P0) were used for two maize hybrids. Results: The interaction of water and P-deficiency (60% and 40% FC along with P50 or P0) reduced the shoot and root traits, and P uptake in both maize cultivars. The activities of SOD, total protein, free proline, and total reducing sugar were increased with decreasing water and P-supply but response of POD and CAT remained variable. The significant upregulation of ZmNAC111 was noted under 40%FC with P100 treatment, but no such effects were recorded under 100%FC at all P treatments in both cultivars. The expression of ZmPHR1.1 and ZmPHR1.2 was increased with reducing P supply, but higher expression was observed at P0 at 60%FC and 40%FC, which indicates these are key genes for P-deficiency tolerance. Conclusions: Overall, P0 with 60% and 40%FC caused severe reductions in growth traits among P levels but 40%FC was most destructive at all levels of P-supply. These findings would be helpful to understand the drought and low P tolerance mechanism of maize and provide future directions for regulation of responsive genes for developing tolerant maize cultivars.