Variabilidade genética em caracteres fisiológicos e de produtividade para o melhoramento genético da batata-doce

Abstract

The objective of this study was to analyze the physiological and productive parameters of sweet potato genotypes and use them as tools for pre-selection aiming at drought tolerance, in addition to evaluating and selecting sweet potato genotypes for different agronomic aptitudes from the joint analysis of tests through two growing seasons. The tests were conducted at the Technology Development and Transfer Center (CDTT/ESAL), belonging to the Federal University of Lavras (UFLA), in Brasil. The experimental station is located in Ijaci, south of Minas Gerais, Brasil. The cycle was 150 days in two trials each, from November to March of the years 2021 and 2022, respectively. The treatments were 52 genotypes from the second round of recurrent selection (C2) and five local commercial checks. The experimental design used was a model with incomplete row and column control. The windrows were spaced one meter apart, built at a height of 0,5 m. The useful plot in each treatment was three meters in the windrow containing 10 plants spaced equidistant from each other. In the drought tolerance test, the evaluations took place in the second season, which consisted of two quantitative measures of biomass accumulation in the root and in leaves and branches, as well as the physiological measures evaluating photosynthesis, stomatal conductance, intracellular CO2 concentration, transpiration, water use efficiency, internal and external carbon ratio, instantaneous carboxylation efficiency, leaf water potential, vigor index, and chlorophyll index. In the other test, in years 1 and 2, 13 characteristics were evaluated, 7 quantitative and 6 qualitative, evaluated together in the two years, with a mixed linear model, adjusted by BLUP and their genotypic correlations, with independent selection of significance by the effect of graphs derived from statistical analyses. The result of the physiological analysis indicated that genotypes 397, 556, 1074, 1404, and 1440 showed high potential as recombinants for a breeding program aimed at drought tolerance. In general, most genotypes showed potential for physiological and productive use for a pre-selection aimed at drought tolerance. The breeding program in this cycle of this population showed physiological and productive potential. The physiological characteristics of the proximal sensor, chlorophyll sensor, and photosynthesis rate, related to the quantitative productivity of dry mass of branches and productivity of dry mass of roots, due to the high genetic variability, were considered key characteristics in the initial selection of potato genotypes -sweet, with practical success in screening directed to the focus of drought tolerance. As for the joint analysis (years 1 and 2), the experimental genotypes outperformed the controls, having multiple characteristics inserted in several genotypes previously not found in traditional cultivars. Genotypes 210, 397, 464, 516, 527, 556, 1074, 1192, 1377, 1404, 1440, and 1476 are highlighted for use in multiple sustainable use skills. Genotypes 397, 516, 556, 1074, and 1404 are suitable for human consumption, animal feed, and ethanol production. Genotypes 1192, 1377, 1440, and 1476 with intense purple pulp are suitable for genetic biofortification. Genotype 464 is suitable for animal feed. Genotype 1440 was highlighted in the commercial pattern. Genotypes 397 and 1268 have a high-quality commercial standard and format. Genotype 556 has high starch accumulation and vigorous development. Genotypes 1476 and 1192 showed a high intensity of purple pulp color, due to the accumulation of anthocyanins in the roots. Genotype 1404 has an excellent shape and growth of compact branches. These presented genotypes have multiple potential uses and should be considered in the continuation of the improvement program for these traits, including other potential uses not yet studied.