Evaluating the Performance of Elite Sweetpotato Genotypes under Stressed and Non-Stressed Conditions Using Drought Tolerance Indices

Abstract

The performance of sweetpotato genotypes under stress conditions due to erratic rainfall patterns can be affected and can result in decreased productivity. About 24 elite sweetpotato genotypes, including one released variety, Alamura, were tested under stress and non-stress conditions in 2022, with the objective of identifying drought-tolerant genotypes for further evaluation and variety development. The trial was established in stress and non-stress blocks using a lattice design arrangement at Werer, Afar Regional State of Ethiopia. Six drought tolerance indices, namely the mean productivity index (MPI), geometric mean productivity (GMP), tolerance (TOL), stress susceptibility index (SSI), stress tolerance index (STI), and stress intensity (SI), were rigorously assessed to select consistently high-yielding genotypes under both conditions. Data were collected specifically for root yield and its components and then subjected to analysis of variance. The result revealed that over eight genotypes performed well under stress conditions for the traits considered. Based on the drought indices, the SI level was 0.23, indicating a 23% yield reduction due to drought stress, which falls within the mild intensity range. In the evaluation of sweetpotato genotypes, if the stress is not severe, correlations of yields under both conditions and drought indices can be assessed. Accordingly, yield in non-stress (YP) and yield in stressful conditions (YS) are positively and significantly associated with stress indices such as MP, GMP, and STI, implying that these indices are appropriate for selecting stress-tolerant and high-yielding genotypes under both stress and non-stress conditions. The correlations were also confirmed with principal component and biplot analyses. Based on these three indices, eight genotypes, namely G4, G6, G9, G10, G13, G17, G19, and G24 were selected as drought-tolerant for further evaluations in multi-location trials.