Choice of parental lines for common bean (Phaseolus vulgaris L.) breeding. 2. Reaction of cultivars and of their segregant populations to variations in different environments

En 6 ambientes diferentes se probaron 12 lineas paternas y 32 poblaciones de segregantes obtenidas de los cruzamientos dialelicos parciales (4 x 8). Las poblaciones F3 se probaron en 1 ambiente, las poblaciones F4 en 2 y las poblaciones F5 en 3. En las 44 poblaciones se determinaron la estabilidad fenotipica del rendimiento de grano, la variacion genetica y ambiental, asi como la variacion de las interacciones ambiente x genotipo para determinar la reaccion de las lineas paternas y de las segregantes a las variaciones ambientales. La interaccion linea paterna x ambiente fue mas del doble que la interaccion segregante x ambiente. Tambien se encontro que los materiales difirieron principalmente en terminos de la desviacion de la regresion y las lineas paternas fueron mas inestables que las poblaciones segregantes, con desviacion significativa de la regresion en 75 por ciento, en contraposicion del solo 28 por ciento en las segregantes. Las poblaciones geneticamente homogeneas (lineas paternas) fueron mas sensibles a la variacion ambiental que las poblaciones geneticamente heterogeneas (segregantes). (RA-CIAT)

Twelve parental lines and 32 segregant populations obtained from partial diallel crosses (4 x 8) were tested in six environments. F3 populations were tested in one environment, F4 populations in two and F5 populations in three. Phenotypic stability of grain yield, genetic and environmental variance, as well as variance of genotype x environment interaction were estimated for the 44 populations to determine the reaction of the parental lines and of the segregants to environmental variations. Parental line x environment interaction was more than double the segregant x environment interaction. The materials were also found to differ mainly in terms of deviation from regression and the parental lines were more unstable than the segregant populations, with significant deviation from regression in 75 percent of them as opposed to only 28 percent in the segregants. We conclude that the genetically homogeneous populations (parental lines) were more sensitive to environmental variation than the genetically heterogeneous populations (segregants). (AS)