The estimation of the common bean grain clarity ('L' value) is a new measure and it is not much used in the breeding programs. The objective of this research was to determine the possibility to classifying common bean genotypes for the 'L' value, within the same commercial group and to evaluate how many repetitions are necessary. Nineteen experiments were conducted in Santa Maria, in Rio Grande do Sul State, Brazil, from 1998/1999 to 2005/2006 years. The grain tegument colors were determined with 13% moisture. The clarity of grain tegument is associated with the commercial value of common bean cultivar. Values between 0.50 and 3.33 were significative different by Tukey test. The clarity of grains tegument ('L' value) can be used to classify common bean lots of same commercial group. Two repetitions are sufficient to evaluate common bean grains tegument colors, with 90% accuracy of the real value and high experimental precision.
Phaseolus vulgaris L.; experimental precision; repeatability; selection; colors of grains
