Growth and Anatomical Alterations in Leaves of Popcorn Induced by Abiotic Stresses

Abstract

Stress by salt and aluminum (Al+3) causes significant loss in the growth of popcorn. Effects on the initial growth, especially of leaves and stomata, are poorly investigated, while no information is available for some cultivars. This work aims at verifying the effect of stress caused by salt and Al+3 on the initial growth, morphometry, and morphology of popcorn stomata (IAC-125), as well as on its foliar anatomy. In the presence of 50 mM or higher concentrations of NaCl, popcorn seedlings showed a reduction of 50% in shoot mass gains as compared to the control. With 150 mM or higher concentrations, mass gains reduced by 33% in popcorn root system as compared to the control. Small increases in shoot length were observed in seedlings treated with Al+3.The root system was highly affected by 160 µM or higher Al+3 concentrations. Pore opening and stomatal subsidiary cell width were altered under both salt and Al+3 stress. Stomatal density changes were observed only under salt stress. Tissue disruptions and cell numberreductions were verified in the epidermis and parenchyma under high Al+3 and saltconcentrations. The largest xylem and phloem cells were preserved in all treatments. Stress resulted in dehydration of plant tissues, which showed retraction under high concentrations of salt and Al+3due to anatomical changes in the leaves and morphometry of the stomata. Our results demonstrated that these characteristics contributed to a remarkable tolerance to salinity and aluminum, since they have an important protective role against different environmental stresses.