The efficiency of a breeding programme with progressively advanced targetsapplied in an elite cultivar of snap bean

The objective of this study was to assess the efficiency of a pedigree intr a-cultivar selection: based on widely spaced individual plant performance, in a traditional snap bean (Phaseolus vulgaris L.) cultivar, aiming to rest ore or even improve the cultivar. The programme started with the target of earliness and yield stability, and was progressively advanced with the targ et of seed shape uniformity. Two parallel pathways were followed: under gre enhouse conditions (four generations of selection) and under field conditio ns (two generations of selection). The average response to selection was 2. 43-3.15 and 0.13-0.42 pods/plant per generation for earliness and yield, re spectively. The coefficient of variability (CV) of earliness decreased from 81.33 to 39.43% and from 61.31 to 42.51% for greenhouse and field grown pr ogenies, respectively. For yield, the CV showed a low decreasing rate, and was stabilized at the end-value of almost 28 %. The results were confirmed during two direct evaluation tests. Firstly, the evaluation of 21 families, as individual spaced plants, showed mean values for earliness of 18.99-22. 94 pods/plant and for yield of 32.89-33.09 pods/plant. Secondly, the evalua tion of improved selections from the greenhouse and the field and of the so urce cultivar, in a dense stand, showed that all the selections produced hi gh and stable early fresh pod harvest even 53 days after planting, while th e control was still at the vegetative phase. The yield of selected progenie s was 219-242 % superior compared with source material. Also, seed stocks o f all selections were of the normal long shape. Short-seed progenies were e xcluded from the breeding programme, since they lacked earliness and stabil ity of performance. The results demonstrate conclusively that it is possibl e to simultaneously improve earliness and pod yield through diminishing pla nt-to-plant variability.