Inheritance of Yield-Related Traits in Climbing Beans (Phaseolus vulgaris L.)

Climbing beans (Phaseolus vulgaris L.) are a traditional crop that has high productivity compared to bush beans. Very little research has been done on climbing beans in comparison to bush beans, and the genetics of its high yield potential are not well understood. The objectives of this work were (i) to evaluate genetic correlations between growth cycle and yield, (ii) to determine the quantitative trait loci (QTL) controlling these phenological and productivity traits, (iii) to compare QTL for seed yield and yield components with QTL for climbing ability in a recombinant inbred line population derived from crossing the climbing bean G2333 by the bush bean G19839, and (iv) to determine heritability for each variable. The experiment was grown on trellises and repeated across four environments, two of which were contrasting for phosphorus fertilization. The results show that inheritance of yield components is simpler and of higher heritability than seed yield itself. Some yield-related QTL were overlapping across environments while others were independent. A total of four QTL were found for yield, while a total of 12 QTL were found for yield component traits. The higher heritability of seed weight allowed the detection of nine QTL for this trait. Meanwhile, a total of six QTL were found for phenological traits, with the majority being for time to maturity rather than time to flowering since the former trait had higher heritability. We discuss the implications of these results for breeding of climbing beans.