The present study was conducted to estimate the genetic variability, heritability, genetic advance and association among selected agronomic traits of common bean landraces from South western Kenya. The field experiment was conducted using 52 common bean landraces at the Kenya Agricultural and Livestock Research Organization (KALRO), Kisii Research Center during 2015 and 2016 main cropping seasons. The experimental design was randomized complete block (RCBD) with three replications. Analysis of variance revealed significant differences indicating the existence of genetic variability among the 52 landraces for 14 quantitative traits studied. The genotypic coefficient of variation ranged from 1.00% for biological yield to 84.69% for pod width, while the phenotypic coefficient of variation ranged from 2.34% for biological yield to 84.40% for number of branches. The estimated broad sense heritability ranged from 60.20% for seeds per plant to 87.57% for days to emergence. Estimates of genetic advance as percent of mean ranged from 10.15% for biological yield to 97.45% for number of branches. Positive and highly significant association of plant height, days from planting to 50% flowering, number of pods per plant and biological yield was observed with seed yield per plant, hence these traits may be directly attributed for the improvement of seed yield. High hereditability and genetic advance was obtained for plant height, 100 seed weight, pod width and number of branches, indicating additive gene effects in controlling the traits and these traits could be used as suitable criteria for selection and improvement of common bean in breeding programs.

Common bean landraces represent an important source of genetic resources, which is under-exploited by Kenyan crop breeding programs. The objective of this study was to characterize 51 common bean landraces from South Western Kenya for resistance to Pythium root rot using 5 peroxidase gene (POX) markers. Following infection with Pythium spp., 11.77, 54.90 and 33.33% of the landraces were moderate-resistant, susceptible and highly susceptible, respectively. A total of 1119 alleles were amplified by the 5 primers, ranging from 3 to 8 alleles per locus. The polymorphism information content (PIC) of the POX markers varied from 0.10 to 0.47. The dendrogram generated using similarity coefficients and un-weighted pair group method with arithmetic averages (UPGMA) did not reveal any unique groupings according to their reaction to Pythium root rot disease. Population structure analysis separated the germplasm into 3 groups and all the groups contained landraces exhibiting both moderate resistance and susceptible to Pythium root rot. The lack of distinct grouping of landraces based on resistance suggests presence of significant genetic variability and different sources of resistance to Pythium root rot. These findings give valuable information for breeders and serve as a baseline for development of cultivars with Pythium root rot resistance.