THE INFLUENCE OF PLANT WATER-STRESS ON NET PHOTOSYNTHESIS AND LEAF-AREA OF 2 MAIZE (ZEA-MAYS L) CULTIVARS

The effect of plant water stress on net photosynthesis and leaf growth were investigated in order to determine to what extent leaf water potential during vegetative growth and silking affects maize development. Two commercial maize hybrids grown in pots in a glasshouse were subjected to leaf water potentials of ‐1300 and ‐1700 kPa during the eighth leaf stage and during silking to ‐1700 and ‐2300 kPa to previously unstressed, moderately and severely stressed plants. The effect of stress on inhibiting CO2 uptake rates and leaf areas, as well as the recovery after alleviating stress, were compared to that of unstressed plants. No substantial differences in CO2 uptake rates were found between medium and long seasoned cultivars. The CO2 uptake rates per unit leaf area decreased to negative values under both moderate and severe stress conditions during both growth stages. During silking, the recovery of CO2 uptake rate was much lower than during the eight leaf stage. Leaf area decreased proportionally with increased stress but did not recover after alleviating stress on plants stressed during both the eighth leaf and silking stages. Copyright © 1990, Wiley Blackwell. All rights reserved