Phenotypic responses of wild barley to experimentally imposed water stress

Responses to water stress within a population of wild barley from Tabigha, Israel, were examined. The population's distribution spans two soil types: Terra Rossa (TR) and Basalt (B). Seeds were collected from plants along a 1 00 m transect; 24 genotypes were sampled from TR and 28 from B. Due to diff erent soil water-holding capacities, plants growing on TR naturally experie nce more intense drought than plants growing on B. In a glasshouse experime nt, water was withheld from plants for two periods (10 d and 14 d) after fl ag leaf emergence. A total of 15 agronomic, morphological, developmental, a nd fertility related traits were examined by analysis of variance (ANOVA). Ten of these traits were significantly affected by the treatment. A high de gree of phenotypic variation was found in the population with significant g enotype x treatment and soil type x treatment interactions. Principal compo nent analysis (PCA) was performed using combined control and stress treatme nt data sets. The first three principal components (pc) explained 88.8% of the variation existing in the population with pc1 (47.9%) comprising yield- related and morphological traits, pc2 (22.9%) developmental characteristics and pc3 (18.0%) fertility-related traits. The relative performance of indi vidual genotypes was determined and water stress tolerant genotypes identif ied. TR genotypes were significantly less affected by the imposed water str ess than B genotypes. Moreover, TR genotypes showed accelerated development under water deficit conditions. Data indicate that specific genotypes demo nstrating differential responses may be useful for comparative physiologica l studies, and that TR genotypes exhibiting yield stability may have value for breeding barley better adapted to drought.