Genotypic variation for drought tolerance in Vicia faba

Instability of yield in faba bean is partly caused by drought susceptibilit y. Four sets with 10-19 faba bean genotypes each were evaluated in multiloc al field trials between 1992 and 1996. Stress occurred as natural drought i n one experiment and as artificial terminal drought in three experiments. A rtificial drought was induced by rain shelters; the control treatment was i rrigated. Tolerance was assessed as the ratio of yield under drought (Yd) t o well-watered yield (Yw). Highly significant variances between genotypes o ccurred; heritability of tolerance was 0.51 < h(2) < 0.88. Exotic (North Af rican, Latin American) genotypes were more tolerant than adapted material. Correlations between Yw and Yd were 0.77** < r < 0.97**, and variance of Yd was less than one-third of the variance of Yw. Drought tolerance was negat ively correlated with Yd (-0.41 < r < -0.22). Relative reduction of plant h eight due to drought was a promising trait to improve drought tolerance ind irectly in two sets. The prospects of improving Yd are good: heritability w as 0.68 < h(2) < 0.86. Genetic improvement of drought tolerance also seems feasible. A specific cross was proposed to create improved material.