Effects of water stress on growth, biomass partitioning, and water-use efficiency in summer maize (Zea mays L.) throughout the growth cycle

The aim of this study was to explore the effects of water stress on the growth, biomass partitioning, and water-use efficiency (WUE) of summer maize (Zea mays L.) throughout the growth cycle. Maize field trials were conducted under a completely randomized design with three field water capacity (FC) regimes. Water was delivered to plants as follows: 75% FC was considered low water stress and the control, 55% FC medium stress, and 35% FC high stress. The controlled irrigation was initiated from the third leaf stage until maturity. The results of 2 years of field trials indicated that maize development and grain yield responses to water stress depended on the severity of stress, including intensity and duration, but also on maize developmental stage. Medium water stress (55%) affected leaf area at the seventeenth (V17) leaf stage, tasseling and silking emergence, leaf extension, and final leaf number to a minor degree. However, 55% FC significantly decreased plant height, leaf area (except for V17), stem diameter, biomass accumulation, net photosynthesis and transpiration rates at different developmental stages. In particular, tasseling and silking, and yield parameters, including ear kernel number and 100-kernel dry weight decreased with increasing medium water stress duration. Severe water stress (35% FC) exhibited increased detrimental effects on all vegetative and yield parameters at different development stages, and resulted in a maturation period delay. Severe stress caused notable reductions in WUE at vegetative and reproductive stages, whereas moderate stress resulted in WUE increases at early and middle stages, and significant decreased WUE at late stages. Overall, these results collectively showed that the negative effects of 2 years of high stress conditions (35% FC) on maize plants were evident in vegetative and yield parameters. We recommend that water deficits or reduced irrigation, and 55% water field capacity, be considered for irrigation scheduling before the maize tasseling stage in neutral loam, meadow soil for sub-humid regions under water limited conditions.