Simultaneous selection in beans for architecture, grain yield and minerals concentration

The objective of this study was to identify the most efficient selection strategy to select common bean lines with erect architecture, high grain yield and high concentration of potassium, phosphorus, zinc and copper in grains. For this purpose, 160 F-6:8 common bean lines and nine parents were evaluated in two growing seasons in Santa Maria/RS, Brazil. The tested selection strategies were direct selection, and six different selection indices were used: classic, base, parameters and weight-free, based on desired gains, multiplicative and rank sum. Two economic weights were established: genetic the variation coefficient and 10 % gain in relation to the mean, tested without restriction (weights in all characters) and with restriction (economic weight equal to zero for two minerals). The grain yield was not correlated with the insertion of the first pod; however, it showed low negative correlation with the potassium (r = -0.29), phosphorus (r = -0.41) and zinc concentrations (r = -0.34) at 1 % probability. The direct selection enabled a high selection gain for individual characters, but caused undesirable changes in the other characters under selection. The selection indices were not in agreement in the identification of superior common bean lines and the use restriction was not advantageous in selection. The multiplicative index is the most efficient strategy of simultaneous selection for erect architecture, high grain yield and high potassium, phosphorus and zinc concentrations in grains in common bean lines. L 72, L 97, L 137 and L 146 are the most promising common bean lines and will be selected to compose the preliminary evaluation trial.