부산대학교 도서관

Plants growing under field conditions are usually subjected to varying degrees of water stress, but the effect of temperature on the development of plant water stress and subsequent recovery is not well‐known. Therefore, a study was conducted in growth chambers to determine the combined effects of temperature and soil water supply on the development of plant water stress and subsequent recovery in spring wheat (Triticum aestivumL. ‘Waldron’). Measurements were made of leaf water potential, photosynthesis, and stomatal diffusion resistance on the fifth leaf at tillering and the flag leaf at heading, flowering, and grain‐filling growth stages for plants grown at 10, 18, and 27C. Stomatal closure of stressed plants was affected by both leaf position and age. Closure occurred at −13, −13, and −15 bars leaf water potential at tillering and at −18, −17, and −26 bars at heading for 10, 18, and 27C, respectively. As the flag leaf matured, stomata closed at progressively lower leaf water potential. In nonstressed check plants, temperature greatly influenced leaf water potentials. At heading, plants at 10C had a significantly lower leaf water potential than plants at 18 and 27C, probably resulting from chill‐induced water stress caused by increased internal resistance to water movement in the plant. At 18C, leaf water potential at tillering and at heading recovered to prestress levels 6 hours after stress ceased, but not until after 48 hours at the grain‐filling stage. Stomatal diffusion resistance recovered to prestress levels within 2 hours, except at grain‐filling, when recovery was incomplete after 48 hours. Recovery of photosynthesis was related to recovery of stomatal diffusion resistance at tillering and heading, except that photosynthesis never fully recovered to prestress levels, and photosynthesis of plants stressed at grainfilling showed no sign of recovery due to stress‐induced senescence.