Selection, Yield Evaluation, Drought Tolerance Indices of Orange-Flesh Sweet potato (Ipomoea batatas Lam) Hybrid Clone

Abstract

Orange-Fleshed Sweet Potato (OFSP) varieties have high pro-vitamin A and medium amounts of iron and zinc. Drought susceptibility is perceived as one of the major drawbacks of this crop type and currently available varieties do not allow sustainable and enduring production in drought affected regions. Screening and selection for OFSP for drought tolerance could have a positive impact on the livelihood and health of vitamin A deficient people in Sub- Saharan Afica (SSA). In this study 18 OFSP genotypes from Lima, Peru and two Kenyan check cultivars, Marooko (drought tolerant) and K566632 (susceptible) were screened for drought tolerance at Kiboko (Latitude 010 15’ S; Longitude 360 44’ E; Altitude 975 masl) and Marigat (Latitude 0° 38, 0” N; Longitude 36° 5, 0” E; Altitude 970 masl) during the years 2008-2009. A split-plot design was used with two levels of treatment, non-irrigated and irrigated as the main factor and the genotypes as the sub-factor. All the treatments were laid out in a randomized complete block design. Stress tolerance index was used to identify genotypes with high stress tolerance and high yield potential. In both site genotypes 194573.9, 420014, 440286, 189135.9, 187017.1 and 441725 showed high stress tolerance and yield potential compared with the check by registering higher stress index that ranged between 0.37- 0.96 and very low susceptibility index. The multidimensional preference analysis of the bi-plot distinguished the same genotypes as high yielding in both treatments imposed. Correlation analysis revealed that Yield potential (Yp) and Stress yield (Ys) had highly significant positive correlation coefficients with Stress Tolerance Index (STI), Mean Productivity (MP) and Geometric Mean Productivity (GMP) and they can be used as the most desirable indices for screening drought tolerance genotypes