Leaf Anatomy of Zea mays L. in Response to Water Shortage and High Temperature: A Comparison of Drought-Resistant and Drought-Sensitive Lines

Leaf anatomical characteristics under normal and reduced water supply in three high-level ABA (abscisic acid) drought-resistant (ZPBL 1304, L-155, and Polj 17) and three low-level ABA drought-sensitive (ZPL 389, B-432, and F-2) lines of Zea mays L. were investigated. The characteristics examined were (1) blade area, (2) thickness of leaf, epidermis, mesophyll, and bulliform cells, (3) stomatal frequency and size of stomatal apparatus, and (4) vessel cross-sectional area. Lines ZPBL 1304 and ZPL 389, L-155 and B-432, and Polj 17 and F-2 were compared. Plant recovery was estimated after exposure to water stress and high-temperature stress. Under normal water supply, the drought-resistant lines were more xeromorphic than the drought-susceptible lines. Water stress affected leaf structures in all lines. Association of xeromorphic features with the ability of the plant to withstand drought varied under dry conditions. Lines ZPL 389, L-155, and Polj 17 were more xeromorphic than lines ZPBL 1304, B-432, and F-2. High temperature induced considerable leaf structural disorganization; however, the changes were not the same in all lines. The greatest differences in leaf structure were observed after the recovery period. The drought-resistant lines showed greater recovery than the drought-sensitive lines. The results, in general, support the hypothesis that cultivars with higher levels of ABA and/or greater drought resistance are more xeromorphic than cultivars with lower levels of ABA and/or lower drought resistance.