Características estruturais e fisiológicas em genótipos de batata-doce e trigo sob déficit hídrico

Abstract

The water deficit affects the morphological, anatomical, and physiological aspects of various plants, which can have a detrimental effect on agronomic and economic production. Current efforts are focused on the development, assessment, and study of new crop genotypes with higher drought tolerance to increase global food production. Therefore, the objective of this study was to evaluate the physiological and morphoanatomical characteristics of four sweet potato genotypes and six wheat genotypes subjected to water deficit, contributing to the identification of drought tolerance or sensitivity. In the sweet potato experiment, four genotypes (UFLA-464, UFLA-1432, UFLA-268, and UFLA-713) were used at two planting times. The first planting time, with a dry autumn/winter climate, had lower precipitation and humidity, while the second planting time, in spring/summer, was rainier. These different climates significantly affected plant growth. The genotypes UFLA-464 and UFLA-1432 showed greater drought resistance due to characteristics that include high gas exchange efficiency, lower water loss, and favorable anatomical adaptations. In contrast, the genotypes UFLA-268 and UFLA-713 require more water and do not exhibit the same drought adaptations. In the wheat experiment, the study was conducted in a greenhouse, using a completely randomized design with 12 treatments (two water conditions and six genotypes) in a factorial scheme (2x6), with five replications and one plant per pot. Wheat genotypes adapted to dry conditions (BRS 404 and MGS Brilhante) and irrigation (BRS 264, Tbio Duque, Tbio Aton, and ORS Feroz) were evaluated. For all genotypes studied under a 30% water deficit of field capacity, an increase in water uses efficiency and anatomical characteristics such as stomatal density, epidermal cell density, vascular bundle area, and phloem area was observed. These characteristics are crucial for resistant genotypes that avoid dehydration, especially in crops with short periods of water deficit and field capacity above 30%, as they help to avoid water stress without compromising morphological and physiological yield. In the study of the anatomy and architecture of roots of different wheat genotypes under water deficit (30% of field capacity), the dry genotype BRS 404 showed better adaptation to drought through anatomical and root architectural modifications. The dry genotype MGS Brilhante showed changes only in anatomical characteristics. Both genotypes demonstrated high phenotypic plasticity in their roots. It is concluded that BRS 404 and MGS Brilhante are more drought-resistant compared to the irrigated genotypes BRS 264, Tbio Duque, Tbio Aton, and ORS Feroz due to their morphoanatomical modifications of the root.