Responses of common bean (Phaseolus vulgaris L.) germoplasm to Macrophomina phaseolina under irrigated and rainfed conditions inVeracruz, Mexico.
experiments were established at Isla and Cotaxtla, Veracruz,
Méxicoto determine the reactions of 56 common bean
genotypes to M. phaseolina under irrigated-rainfed conditions
and to identify resistant and stable-yielding germplasms under
water-stress conditions. The germplasm included different
origins, genetic races, seed coat colors and genetic status and
was randomized in 7x8 lattice experimental designs and then
grown under irrigated and rainfed conditions (no irrigation
throughout the reproductive stage). Water stress promoted
earlier physiological maturity and increased charcoal rot
severity; in addition, water stress reduced common bean grain
yields. Through the four experiments TLP20/NT81, NGO
99165, Negro Veracruz, A 774, and BAT 477 showed the
highest grain yields (more than 1000 kg ha-1) and the lowest
charcoal rot severity ratings, while Negro Otomí, 9457-43,
NGO 99176, CNC 2, and VAX 2 showed an inverse behaviour.
Drought Intensity Index varied through experiments although
the highest values were found at Isla (0.53 and 0.38 in 2000
and 2001, respectively). No clear association between Drought
Susceptibility Index and charcoal rot severity or grain yield
were found, but a negative relationship between grain yield and
charcoal rot severity was registered (r = -0.26*) en promedio.
Although no clear associations were found, the genotypes with
the lowest M. phaseolina damages and the highest grain yields
showed low values of drought susceptibility index.