Heterosis and inheritance of drought tolerance in faba bean, Vicia faba L.

Twelve parental lines of faba beans and 27 F-1 hybrids derived from them were field-tested under a dry and a well-watered treatment, at two German locations (Gottingen, Hohenheim) in two years (1995, 1996). Drought was artificially induced using rain shelters from anthesis until maturity. Data were collected on yield under dry (Yd) and well-watered (Yw) conditions. Drought tolerance was assessed as Yd/Yw. The midparent heterosis was significant for Yd and Yw, but not for Yd/Yw. Relative heterosis for Yd (52.0%) was greater than for Yw (39.3%). Parental heritability was greater for Yw (0.86) than for Yd (0.61). However, it was similar for both traits in F-1 hybrids (0.65 and 0.66). Principal component analysis showed that F-1 hybrids exhibited the same pattern of adaptation as their parents. The heritability of drought tolerance was 0.48 in F-1 hybrids and 0.70 in parents. Attention should be paid to its negative correlation with yield. Several hybrids combined high tolerance, a favourable pattern of adaptation and appropriate performance.