Morphophysiology, morphoanatomy, and grain yield under field conditions for two maize hybrids with contrasting response to drought stress

In the northern region of the state of Minas Gerais, lack of rainfall limits crop production in the field, which is possible only with irrigation. Agricultural and physiological practices have been intensively searched to overcome drought effects and consequently increase production. In this context, the objective of this study was to characterize morphophysiological and morphoanatomical changes and evaluate the attributes of grain yield under field conditions in two hybrids contrasting for drought tolerance. The experiment was carried out for 2 years (2010 and 2011) and the water deficit was imposed by stopping irrigation for 22 days at the pre-flowering stage. At the end of the stress treatment, leaf and root anatomy and morphophysiological characteristics (leaf water potential, chlorophyll content, percentage of dry leaves, leaf area, stomatal conductance, chlorophyll fluorescence, and anthesis-silking interval) were evaluated. For a better interpretation of tolerance of the hybrids in the evaluated characteristics, an index was used stress index. Hybrid DKB 390 (tolerant) surpassed hybrid BRS 1030 (sensitive) in grain yield. Furthermore, it presented lower percentage of dry leaves, higher flowering synchronization, higher stomatal conductance, and higher Fv/Fm relationship. In the root, DKB 390 showed higher amount of aerenchyma in the cortex, an increase of exodermis width, and numerous metaxylem with smaller diameter. In the leaf, it presented higher number of stomata and smaller distance between the vascular bundles in the leaf blade. The study concluded that significant morphophysiological and morphoanatomical changes, which are related to drought tolerance, occurred in DKB 390, leading to a higher yield in the field.