Effects of water stress on leaf respiration, transpiration rates in the dark and cuticular resistance to water vapor diffusion of two corn inbreds

Growth chamber studies were undertaken to determine relationships between leaf respiration and transpiration in the dark, and leaf water potential. Leaf cuticular resistances were calculated. Two lines of corn (Zea mays L.), one a wilting inbred line, Q188, and the other, DR1, an inbred line known to have at least some heat and drought tolerance under field conditions were used in this study. Differences were found in dark transpiration and the magnitude of cuticular resistances to water vapor diffusion between these lines. Dark transpiration occurred at a greater rate in Q188 than in DR1. Both lines showed decreased transpiration as leaf water potentials decreased and were not significantly different in this respect. Cuticular resistance to water vapor diffusion was higher initially in DR1 than in Q188 and also increased at a faster rate in DR1 as the drying cycle progressed. Incomplete recovery in leaf water potential was observed in both lines upon watering after severe desiccation. No differences were found in leaf respiration rates between the inbreds.