Effect of water shortage on six potato genotypes in the highlands of Bolivia (II): water relations, physiological parameters

Abstract

Six potato genotypes were grown in containers in the highlands of Bolivia under three water regimes: R0 (well-irrigated controls); R1 (progressive drought after tuberisation and recovery period), and R2 (no recovery). Soil water content (theta(w)), leaf relative water deficit (RWD), leaf water potential (psi(w)), stomatal resistance (r(s)) and chlorophyll fluorescence were evaluated. The objective of this research was to characterise the drought adaptation of the potato genotypes studied, and to identify physiological indicators of drought tolerance. Under drought conditions, cultivar Alpha maintained the highest theta(w) and the lowest RWD. Cultivar Luky exhibited a high r(s) and cultivar Alpha showed the lowest r(s), especially at the end of the R2 treatment. The relations RWD-psi(w), theta(w)-RWD and theta(m)-psi(w) were not affected by genotype or treatment. Chlorophyll fluorescence measurements revealed, in all genotypes, a very high drought resistance of the photosynthetic apparatus, which was not affected in a RWD range of 0-50%. No significant correlation was found between tuber yield and the measured physiological parameters.