Abstract
The influence of temperature and water stress on the leaf water status of two snap bean (Phaseolus vulgaris L.) cultivars was examined in glasshouse experiments in Ishigaki, Okinawa, Japan. Haibushi, a high temperature-tolerant and Kentucky Wonder, a high temperature-sensitive cultivar, were grown under normal (27/23°C, day/night) and high (31/27°C) temperature regimes, and water stress was imposed at the 3-leaf (vegetative phase) and podding (reproductive phase) stages. The leaf water potential (LWP) in the two cultivars declined daily at 1100 hr under a 27/23°C regime (hereafter referred as “at 27/23°C”), but continuously declined at 31/27°C. This trend was more conspicuous in Kentucky Wonder than in Haibushi. Significant cultivar, temperature and water stress interactions for the leaf water status were observed on several occasions at both growth stages. The effect of the temperature and water stress was more pronounced at the podding than at the 3-leaf stage. Differences in RWC became more appreciable at high than normal temperatures, especially at the podding stage. Haibushi showed a faster recovery of the water status than Kentucky Wonder at the 3-leaf stage. The latter showed wilting at the podding stage unlike the former. The relationship between RWC and LWP was examined separately for the two cultivars in the temperature and water stress treatments. Haibushi showed a smaller decrease in RWC with LWP than Kentucky Wonder. These genotypic differences in the water status could further be exploited to identify and develop improved snap bean cultivars tolerant to water and high temperature stresses.
