Pre-breeding manipulations for pod yield stability in a snap bean cultivar

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SummaryThe objective of this study was to present pre-breeding manipulations for decreasing the magnitude of the environment-dependent performance of a climbing type snap bean (Phaseolus vulgaris L.) cultivar. The cultivar was exposed to abiotic diversity, by planting on three dates for two successive years, 1997 and 1998. In the first year, three statistical analyses were followed: i) partition of variance, which defined a significant planting date × pod measurement interaction, ii) regression analysis, which showed that temperature accumulation for each environment was highly correlated (r = 0.97) with pod yield, and iii) pod-yield frequency distributions of space-planted single plants, which showed positive skewness for all measurements, while the high coefficient of variability (CV) values quantified the genotype × environment interaction. Preliminary selection on single-plant performance for earliness and yield resulted in 12 first-generation progenies. In the second year, the frequency distribution profile for earliness and pod yield performance per se of the progenies showed improved stability of performance and resulted in 92 second-generation progenies for further exploitation. Colour abnormalities in the dry seed product of the second-generation progenies were studied in 1999 and showed a phenotypic origin of the colour variation. Conclusively, the pre-breeding manipulations resulted in gaining pod yield stability by using the isolation environment for planting, the yield performance per se for evaluating genotypes and the yield frequency distributions based on CV values for estimating stability.