Transpiration efficiency of corn hybrids at different growth stages

Understanding transpiration efficiency (TE), especially in water-limited environments, is likely to result in increased crop yield. Two successive greenhouse experiments were conducted in 2017 to determine season-long TE in three corn (Zea mays L.) hybrids (P1151AM, 33D53AM, and P1564HR) and investigate whether the TE varies among different plant growth stages (six-leaf, flag leaf, mid-grain filling, and physiological maturity). Corn plants were grown in wooden boxes up to maturity while eliminating water loss except that lost in the form of transpiration. To prevent the belowground water loss, wooden boxes were lined with plastic sheets and sealed to the lids. The TE was determined as the ratio of aboveground biomass to cumulative water used in transpiration. The mean TE was the highest (6.27 kg m(-3)) when plants were harvested at the mid-grain-filling stage, followed by the flag leaf stage (5.91 kg m(-3)), and physiological maturity (5.81 kg m(-3)), and lowest at the six-leaf stage (5.25 kg m(-3)). Two-drought tolerant (DT) hybrids, P1151AM (6.20 kg m(-3)) and P1564HR (6.17 kg m(-3)), had higher TE than the conventional hybrid, 33D53AM (5.42 kg m(-3)). Grain-filling period is critical for water management in corn. This study showed that TE was also highest when plants were harvested at the mid-grain-filling stage and decreased thereafter. Therefore, producers, who have limited irrigation facilities, should develop a strategy to apply a sufficient amount of water before and during the grain-filling period for maximizing corn yield.