Flooding, growth and leaf gas exchange of wax-apple trees in containers
Keywords:Syzygium samarangense, Anoxia, Stomatal conductance, CO2 exchange rate, lnternal CO2 concentration, O2 consumption rate
AbstractThe vegetative growth of the wax-apple (Syzygium samarangense Merr. et Perry) tree was correlated with its physiological responses under flooding stress. Container-grown wax-apple trees were treated with various intervals of flooding. Growth response of new shoot and root system as well as leaf gas exchange among various treatments were compared. The first flush growth of new shoots for the treatments of 14-42 days of flooding were significantly lower than those of the control. The shoots of 14-, 28-, and 42-day flooded plants started the second flush growth at the 37th, 44th, and 72nd day, respectively. The second flush growth of the 42-day treatment was significantly lower than that of non-flooding control, 14-, and 28-day flooded treatments. The root dry weights of 14-, 28-, and 42-day flooded plants were 78.5, 72.9, and 61.7% of the control, respectively. The stomatal conductances, CO2 exchange rates, and transpiration rates of wax-apple leaves had similar variation trends during flooding. Their values decreased after 24 h of flooding but returned to the level of the control after 14 days of de-flooding, while the internal CO2 concentration in leaves remained similar. Oxygen consumption rates of fibrous roots of 7-, 14-, 28-, and 42-day flooded plants were lowered to 64, 53, 47, and 46% of the level of the control, respectively.