Responses of Physiological Traits of Maize to Water Deficit Induced at Different Phenological Stages

Abstract

Two field experiments were conducted to evaluate the physiological responses of maize to water deficit conditions. Five water regimes (control, water deficit from V10 to V13, V13 to V17, V17 to blister and blister to physiological maturity) and 3 maize genotypes including Pioneer 30B80, NK 40 and Suwan 4452 were tested under moderate water deficit (MWD). Based on their better physiological performance, NK 40 and Suwan 4452 were further evaluated under severe water deficit (SWD) levels (control, water deficit from V10 to anthesis, anthesis to milk and milk to physiological maturity). The omission of irrigation in the moderate and severe water deficit regimes decreased the soil water potential and resulted in a significant decrease in the relative water content (RWC), chlorophyll content, leaf area (LA) and dry matter (DM) accumulation compared to the control. A greater decrease in the RWC (13.66 and 29.78%) at the V17 and anthesis stages, chlorophyll content (12.75 and 49.44%) at the V17 and late grain filling stages, LA (50.01 and 36.64%) at the V13 and milk stages and DM (15.98 and 14.60%) at the V17 and late grain filling stages was found under moderate and severe water deficit, respectively. The most susceptible stage to MWD and SWD was the V13 to V17 stage and the anthesis to milk stage, respectively in terms of grain yield reduction. After rewatering, the RWC fully recovered or was close to the control level under both water deficits while recovery of chlorophyll was relatively higher in the moderate water stress regime. Rewatering after water deficit at an early stage resulted in a recovery in leaf area but rewatering after anthesis failed to recover leaf area under both experiments. NK 40 demonstrated better performance regarding sustaining a relatively higher RWC and chlorophyll content and a higher yield under both stress environments compared to the other genotypes. The relative water content, chlorophyll content and grain yield showed negative relationships with the available soil water depletion (%), while the grain yield showed a positive relationship with the relative water content and chlorophyll content under both water deficit experiments which can be used as an index for drought screening.