Genotypic response of faba bean to water stress

Faba bean (Vicia faba L.) improvement programs in the Mediterranean area ai m to select genotypes showing high and stable yields. Water stress is a mai n factor limiting faba bean yields and, as for other crops, new parameters of selection (morphological, physiological and biochemical) are being teste d to identify genotypes tolerant to water stress. This study reports the re sponse of eight faba bean improved populations and two cultivars to water s tress. All genotypes were grown in large containers protected from rainfall by a transparent plastic covering and subjected to simulated water stress. In non-stress and stress conditions, water status was recorded by means of leaf water potential (LWP) and stomatal resistance (Rs) measurements. Furt hermore, genotypes were evaluated for the main bio-agronomic traits, abscis ic acid content, and an index of genotype susceptibility to water stress wa s calculated. Finally, in order to obtain useful information on selection c riteria to use in breeding programs for tolerance to water stress, a correl ation analysis among traits was performed. The results showed LWP and Rs me asurements were useful in describing the simulated water stress, but were n ot very suitable for discriminating genotypes with tolerance to water stres s. The use of the genotype susceptibility index was effective in estimating different genotypic responses to water stress, while the abscisic acid (AB A) determinations did not provide any useful information about the efficaci ous utilization of this parameter in programs of breeding for tolerance to water stress.