Tolerância de genótipos de batata-doce ao déficit hídrico

Abstract

Sweet potato (Ipomoea batatas (L.) Lam.) is one of the most economically important vegetables and one of the most widely cultivated worldwide, with production concentrated in Asia and Africa. Despite the relevance of this crop in Brazil, the country ranks only 14th among the world’s largest, sweet potato producers. This is due, among other factors, to the low technological levels adopted in cultivation, such as the scarcity of genotypes adapted to different regions under water deficit, which results in yields far below the crop’s potential. The objective of this study was to select drought-tolerant sweet potato genotypes from the breeding program conducted at UFLA. The experiments were carried out in a greenhouse located in the Vegetable Production Sector of the Department of Agriculture at UFLA. The institution is located in the municipality of Lavras, southern Minas Gerais state, at an altitude of 910 meters. The crop cycle lasted 150 days in two trials conducted from December to May of the 2022/2023 and 2023/2024 growing seasons, respectively. The experimental design used in each trial was completely randomized (CRD), in a 28 × 4 × 2 factorial scheme, consisting of 28 sweet potato genotypes, four irrigation levels (25, 50, 75, and 100% of crop water requirement), and two years of cultivation, with a semi-automatic drip irrigation system. In each experiment, the experimental unit consisted of a 10 dm3 pot with three replications, totaling 336 pots. Irrigation was applied via drip emitters with a flow rate of 4 L h−1. Soil moisture was monitored using 10HS sensors and ProCheck data loggers, based on field capacity. The 100% irrigation level served as a reference to calculate replenishment at 25%, 50%, 75%, and 100%. The agronomic variables evaluated were shoot yield, shoot dry mass, storage root yield, storage root dry mass, and total biomass yield, based on water productivity as an indicator of drought tolerance, as well as through drought tolerance selection indices (drought intensity index, drought tolerance efficiency, and percentage reduction). Statistical analysis was performed using R software version 4.1.1 (R Core Team, 2024), with the Scott- Knott test (p < 0.05). Significant differences were observed among genotypes and irrigation levels for water productivity in all evaluated variables. Under the irrigation level of 25% of maximum crop water requirement, the main stress condition, the best results were observed for cultivars UFLA R1440, Olga, Super Margaret, and Irene. These same cultivars also showed the best results under the drought tolerance selection index evaluation. The cultivars identified in this study showed potential for use in breeding programs aimed at drought tolerance, especially in regions with low water availability.