PHYSIOLOGICAL PERFORMANCE OF MAIZE (ZEA MAYS L.) UNDER STRESS CONDITIONS OF WATER DEFICIT AND HIGH TEMPERATURE

The effect of water deficit is usually consistent with the influence of high temperature. In order to evaluate each of the two factors on the physiological performance of six maize (Zea mays L.) hybrids independently, two different experiments have been conducted in the field and the greenhouse. Physiological processes in different vegetative growth stages V10, V14, VT and reproductive growth stage R3 were studied. Photosynthetic rate (Pn), transpiration rate (E), and stomatal conductance (gs) as well as specific leaf area (SLA) were examined. Four different water levels were used, while I-1 was well irrigated, on the other levels water deficit was created, in I(2 )in the vegetative growth period, in I-3 in the reproductive growth period and in I-4 at both vegetative and reproductive periods. The rate of photosynthesis of all six hybrids was increased from V10 to R3 under the effect of I-1, while variations in other physiological performance were correlated with water levels and also with the tolerance potential of maize hybrids. The influence of water deficit treatments combined with the effect of high temperature limited the efficiency of physiological traits especially photosynthesis. The consistency between leaf area and the amount of dry matter that partitioned to the leaves was behaved for maintaining the photosynthetic area under stress condition. The greatest change in the rate of the physiological traits of all hybrids occurred with raising the temperature from T-1 to T-4 in the greenhouse.