Batata-doce x seca: respostas fisiológicas, bioquímicas e morfológicas e seleção de genótipos tolerantes por meio de índice multivariado

Abstract

Sweet potato is a crop of great socioeconomic importance, however, Brazilian production systems have low productivity, mainly due to the use of obsolete genotypes that are not very tolerant to stress and inadequate management. Stress due to water scarcity leads to decreased productivity and quality of sweet potato, as it negatively affects vital processes, such as photosynthesis and translocation of photoassimilates. Given the above, with the ultimate goal of understanding how water deficit affects sweet potato and identifying tolerant genotypes, this work was divided into: (1) evaluation of the physiological, biochemical and morphological responses of sweet potato genotypes subjected to water deficit; (2) identification of genotypes tolerant to water deficit using a multivariate index. The experiment was carried out in a greenhouse, in a completely randomized design with four replicates. Twenty sweet potato genotypes and two water replacement rates (20 and 100% of pot capacity) were evaluated. Biochemical characteristics, chlorophyll fluorescence, pigment content, leaf gas exchange, leaf water potential and biometric aspects of shoots and roots were evaluated. Chlorophyll fluorescence and pigment content were evaluated over a period of five weeks. When evaluating the different sweet potato genotypes, a wide range of physiological and biochemical responses to water deficit were identified. The results indicate that drought tolerance is a multifactorial process. The genotypes ‘Luiza’, ‘Canadense’, ‘CIP 420717', ‘Maria Isabel' and ‘CIP 440186' demonstrated superior performance in relation to drought tolerance, based on the parameters evaluated. The joint analysis of characteristics (MGIDI) allowed a more complete understanding of the resistance mechanisms facilitating the selection of superior genotypes, ‘Minerinha’, ‘Canadense’, ‘IAC Clara’, ‘Japonesa’, ‘CIP 440003’, CIP 400092’, ‘CIP 440178’, ‘Luiza’ ‘CIP 187012/2’ and ‘Maria Isabel’ are the genotypes closest to the idéotype in the water deficit condition.