Water-deficit tolerant identification in sweet potato genotypes (Ipomoea batatas (L.) Lam.) in vegetative developmental stage using multivariate physiological indices

Abstract

Sweet potato (Ipomoea batatas [L.] Lam.) is one of three main storage root crops of global importance after potato and cassava. It serves as the primary source of carbohydrate for the world population in developing countries. Sweet potato has been reported as drought sensitive, especially in the rain fed region with extended drought condition. Some cultivars might be more tolerant to drought stress compared to others. We investigated the physiological and morphological responses and storage root yield attributes of 6 sweet potato genotypes (cvs. Manphuang and Mankorat, PROC 65-3, Banyang 9, Tainung 57 and Japanese yellow) to water deficit stress (15% SWC) with an aim to classify the water deficit tolerance using the relationship between free proline and osmotic adjustments. Osmotic potential (Ψs), chlorophyll b (Chlb), maximum quantum yield of PSII (Fv/Fm), plant height and number of leaves in sweet potato cv. PROC 65-3 grown under water deficit condition (15% SWC) were better than those in other cultivars. The yield reduction, growth inhibition, free proline enrichment, osmotic potential maintaining, chlorophyll degradation, chlorophyll fluorescence diminution, net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (E) reduction in water deficit stressed plants were subjected to Ward's cluster analysis. Mankorat, PROC 65-3 and Japanese Yellow were classified as water deficit tolerance whereas Manphuang, Banyang 9 and Tainung 57 genotypes were evaluated as water deficit sensitive. The study concludes that free proline accumulation may play a key role as major osmotic adjustment in sweet potato and negative correlated with osmotic potential of leaf tissues when plants subjected to water deficit. © 2013 Elsevier B.V.