Leaf anatomical characteristics and physiological responses to short-term drought in Ziziphus mauritiana (Lamk.)

The aim of this work was to study the association between leaf anatomical characteristics and response to short-term drought stress in Ziziphus mauritiana Lamk. Six Z. mauritiana cultivars (Seb, Cola, Umran, Keitly, Q-29 and B-5/4) under field conditions in Israel's Negev desert were studied. Width of palisade mesophyll, spongy mesophyll and epidermis, xylem number and diameter in mid-vein were investigated with light microscopy. Short-term (3 weeks) drought stress tolerance was evaluated by monitoring plant response (leaf transpiration, diffusive resistance, chlorophyll fluorescence, leaf water potential and leaf relative water content). Greater epidermis and mesophyll widths and xylem diameters and densities were associated with increased tolerance to short-term water deficit expressed by preliminary wilting symptoms and proportional differences between initial and final physiological parameters. Significantly larger differences were found in Keitly, Umran and B-5/4 than in Seb, Cola and Q-29, indicating that the former cultivars are more sensitive to drought stress. Our results indicate that tolerance in descending order was Seb, Q-29, Cola, B-5/4, Keitly and finally Umran. The existence of an association between anatomical characteristics and short-term drought stress tolerance based on physiological responses is suggested. (C) 2010 Elsevier By. All rights reserved.