Selection of Biofortified Sweet Potato (Ipomoea batatas L.) Genotypes in Response to Drought Stress

The development of orange- and purple-fleshed sweet potato genotypes with high nutritional quality and drought tolerance is paramount in the face of climate changes and exponential human population growth. Therefore, the objective was to select biofortified sweet potato genotypes tolerant to drought. Eight progenies developed by the NEOSC-UFSC group and one commercial genotype were grown in field and greenhouse conditions with drought periods. In the field trial, the plants were grown with very low rainfall from the 4th to the 13th and from 17th to the 18th weeks after planting (WAP). In the greenhouse trial, irrigation was suspended from the 4th to the 7th and 11th to 14th WAP (drought) or maintained throughout the experiment (control). The production of tuberous roots was evaluated in both trials, while biomass, gas exchanges, chlorophyll fluorescence, chlorophyll index, electrolyte leakage, relative water content, wilting tolerance and post-harvest attributes were determined in the greenhouse trial. The contents of phenolics and flavonoids did not differ among genotypes, which showed small colour variation in response to drought. Water deficit increased electrolyte leakage and reduced yield in all genotypes, which had different responses to drought, modulating gas exchanges, biomass partitioning, energy allocation and defences. The white-fleshed FW-42 and LW-102 and the purple-fleshed LP-115 and LP-75 were the most productive and the most tolerant to drought stress genotypes. These genotypes also showed higher yield than the global average and the commercial Brazlândia branca, pointing to their great potential to be used under well-water and drought conditions, providing higher nutritional quality.