Morpho-anatomical characterization of root in recurrent selection cycles for flood tolerance of maize (Zea mays L.)

Changes in root anatomical structures at successive cycles of selection (cycle 1 to cycle 18, alternating) were observed in the study of maize (Zea mays L. cv. Saracura-BRS 4154) capable to survive and produce in temporarily flooded soils; this cultivars was developed by the Maize and Sorghum National Research Center through stratified phenotypic recurrent selection for cultivation wetland soils. Field trial was carried out and flooding of the soil was initiated at the six-leaf stage; the soil was flooded with water (20-cm deep) three times per week. Root sample was collected, fixed, and selected for observation in photon microscope. A gradual increase in the number of aerenchyma, the proportion of vascular cylinder, smaller metaxylem, and phloem and epidermis width, and a decrease in exodermis and cortex were observed in successive selection cycles. Such phenotypic changes impart the flood tolerance ability to this maize cultivar.