Effects of Drought Stress on Sap Flow, Stomatal Conductance, and Leaf Water Potential of Pepper Cultivars (Capsicum annuum L.)

摘要

Drought has been an increasing threat to agricultural production because of excess ground water use and accelerating global environmental changes. Therefore, it is urgent to elucidate the plant mechanism against drought stress and to accumulate information for the breeding of stress tolerant cultivars. The Thai Chilli and New Ace pepper cultivars {Capsicum annuum L), displaying contrasting physiological characteristics in response to environmental stress, were examined in relation to drought stress conditions. Methods used for the experiments included: heat pulse method to measure the sap flow rate, in addition to the monitoring stomatal conductance and leaf water potential. Thai Chilli displayed a higher sensitivity to drought, which, in turn, seemed to facilitate the prevention of excess water loss under limited water availability condition. Also, compared with New Ace, Thai Chilli exhibited an earlier recovery in sap flow, stomatal conductance, and leaf water potential after irrigation resumed. Also, plants from the preliminary drought stress treatment showed a higher tolerance to subsequent stress than the plants those where not exposed to stress. Variation in drought stress tolerance among pepper cultivars might have stemmed from physiological and morphological differences, such as leaf shape, cell and root structure, and regulation ability of leaf water potential.