Search

Common bean (Phaseolus vulgaris L.) is a staple and nutritious leguminous food crop for all income categories in Africa. Efforts to improve its yield performance and nutritional components, especially iron and zinc have resulted in release of several varieties in the sub-Sahara African region. The objective of this study was to assess genetic progress in varieties released in 12 African countries through the Pan African Bean Research Alliance (PABRA) from 1973 to 2017, to inform current breeding decisions. A total of 214 released varieties, land races and breeding lines, of bush and climbing beans were evaluated for yield, micronutrient (Fe and Zn) concentration, and phenology in three locations (Kawanda and Kachwekano in Uganda, and Kitengule in Tanzania) in 2017/2018. There were significant differences (P<0.01) among genotypes for all traits, except days to maturity (DPM). Genotype x environment interaction was also significant (P<0.05) for all assessed traits, except for iron in climbing beans. Across environments, repeatability (H²) was greater than 0.50 for all traits, except for DPM in climbing beans. Annual rates of genetic yield gains were 4.41 and 4.57 kg ha-1 for large and small seed bush beans, and -2.74 and 21.6 kg ha-1 for large and small seeded climbers. Similarly, gains in seed iron (FESEED) were 0.40 and 0.17 ppm for bush and climbing beans, respectively. These represented an annual relative gain over the oldest varieties of 0.6 and 0.7% kg ha-1 for yield of large and small seeded bush beans, -0.3 and 1.6% kg ha-1 for yield of large and small seeded climbers, 0.6 and 0.2% ppm for FESEED of bush and climbers. Overall, genetic progress was slow for both yield and FESEED. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) provides dietary protein, energy, fiber, and micronutrients, especially iron and zinc to over 800 million people in Africa and Latin America. The crop has various seed types. White beans are very popular for the processing industry. This study aimed to investigate the agronomic performance, canning quality, cooking time (COOKT) and response to root rots (Fusarium cuneirostrum and Pythium ultimum) and angular leaf spot (ALS; Pseudocercospora griseola) diseases among 151 drought tolerant small and large seeded white bean genotypes from trials conducted between 2013 to 2018 in East Africa. Significant (P<0.001) differences existed among the genotypes for response to the three pathogens, COOKT and canning quality traits. Resistance to each of the pathogens was expressed in 24-75% of the genotypes, while dual resistance to any two pairs of the pathogens occurred in 10-44% of the genotypes. Four genotypes; ICNBunsixSxB405/4C- 1C-1C-88, RAZ-11, ETSNAP18 and ETSNAP3 expressed resistance to the three pathogens but had COOKT of 46-56 minutes (based on a Matson cooker), and below average canning quality. They are recommended as sources of diseases resistance but could be further improved for COOKT and canning quality. Sixty-eight genotypes had COOKT <50 minutes while 24 expressed good to excellent visual canning quality. Some phenotypes: RAZ-120, RAZ36-Caballero, NavyLine-60, NavyLine-25, ZABR16573-25F22, ZABR16575-60F22, ETSNAP33, Bifortsmallseeded-15 and ZABR16574-37F22, that were cooked in <45 minutes, exhibited good to excellent canning quality and expressed resistant to intermediate diseases resistance responses. These may be used as parental lines and/or fast tracked for variety release through regional trials. [ABSTRACT FROM AUTHOR]

Root rots cause severe yield losses of up to >70% in common bean (Phaseolus vulgaris L.) in most parts of the world, with devastating effects on the major commercial bean cultivars in East and Central Africa. Increased intensity of droughts and rains, and higher temperatures influence the occurrence and distribution of root rots, resulting in increased epidemics. The causal pathogens tend to occur in a complex, and since most cultivars do not have broad resistance, adverse effects continue to occur. The objective of this study was to evaluate the levels of dual resistance of new breeding lines (BL) developed for root rot resistance, as well as Andean (ADP) genotypes, for resistance to Fusarium (FRR) and Pythium root rots (PRR). Altogether, 316 new BL developed for root rot resistance and 295 ADP bean genotypes were evaluated at Kawanda in Uganda. There were significant differences (P<0.05) among genotypes for both root rots and yield. Thirty and 1.9 percent of the BL and ADP genotypes expressed resistance to both root rots. In addition, more than 80% of ADP genotypes showed susceptibility to both root rots. Yield was generally poor with means of 458 kg ha-1 for ADP, and ranging from 949 to 1075 kg ha-1 for the BL groups. Nonetheless, the 0.3 and 2.4% of the ADP and BL that yielded >2000 kg ha-1 expressed high yield potential, considering that majority of the genotypes yielded below 1000 kg ha-1. [ABSTRACT FROM AUTHOR]