EPICUTICULAR WAX MORPHOLOGY OF SOYBEAN LEAVES UNDER WATER DEFICIENCY.

VARILLAS, M.A.; FIORETTI, M.N.; BAIONI, S.S.; AVELDAÑO, M.I.; BREVEDAN, R.E.

Tandil, Argentina

Congreso; X Congreso Argentino de Ciencias Morfológicas; 2006

Our objective was to determine the morphological changes of epicuticular waxes in leaves of soybean plants grown under high and low irrigation conditions (HI and LI, respectively). The water status of the plant (leaf water potential, stomatal conductance and leaf relative water content) was significantly higher in plants grown in HI than LI-soils. LI treatment resulted in a significant decrease in the dry weight of the stems and leaves which was correlated with a significant decrease in leaf area in comparison with HI-plants. Scanning electron microscopy analysis showed that the epicuticular wax film consisted of an amorphous deposit with irregularly edged plates, arranged perpendicular to the leaf surface. These plates were uniformly distributed over the entire surface of the leaves. The wax film of the abaxial leaf plane consisted of deposits of a material of similar fine structure but much denser in LI than in HI plants. The total wax content per unit leaf area increased almost 3 times in LI compared with HI plants. The wax composition also changed, since all components augmented, the most hydrophobic constituents increased the most. Among these were the very long odd-chain alkanes (C25 to C31). The chemical alteration in the leaf wax content and composition may represent physiological-adaptive responses of soybean plants to water stress.