Rowland Chirwa

Adaptability and Stability of Bean Cultivars as Determined via Yield-Stability Statistic and GGE Biplot Analysis

Abstract International centers, such as CIAT, routinely conduct crop performance tests across years and locations internationally, generating valuable multienvironment trial (MET) data. These data must be properly evaluated and interpreted to enhance efficiency of breeding/ testing programs. The purposes of this study were to identify superior bean (Phaseolus vulgaris) cultivars from MET conducted from 1995–2002 in eight southern African countries and to evaluate test locations to improve testing efficiency. Analyses of variance by year across locations revealed significant variation among cultivars in seven years as well as significant variation associated with cultivar-by-location interaction in all eight years. Kangs YS; statistic and GGE biplot methodology based on principal-component analysis helped identify cultivars that had general and/or specific adaptation across/to locations. These methods were also useful in identifying cultivars whose stability/instability was influenced by the linear effect of environmental index. The GGE biplot methodology helped identify redundant and/or non-informative locations. We conclude that the number of test sites used for screening of germplasm in CIATs southern African bean program can easily be reduced. Elimination of some of the redundant locations could save the CIATs common bean testing program valuable resources, such as time, labor, and money. Greater use should be made of those test locations that showed greater differentiation among cultivars, e.g., Bembeke, Chitedze, and Delmas. The use of environmental index as a covariate provided only limited amount of information. In half of the trials, the linear effect of environmental index affected the stability of certain cultivars.

Andean beans (Phaseolus vulgaris L.) with resistance to the angular leaf spot pathogen (Phaeoisariopsis griseola) in southern and eastern Africa

Common beans (Phaseolus vulgaris) are separated into two distinct groups: Andean and Middle American. We identified CAL 143 as the first Andean bean with resistance to angular leaf spot disease caused by Phaeoisariopsis griseola. Angular leaf spot is the most widespread and economically important bean disease in southern and eastern Africa, and it is especially severe on the extensively grown Andean beans. Cal 143 was resistant in Malawi, South Africa, Tanzania, and Zambia, but it was susceptible in Uganda. This was attributed to the presence of races of P. griseola in Uganda not present in the other countries. We identified two additional Andean bean lines, AND 277 and AND 279, with resistance to angular leaf spot in Malawi. We also characterized the virulence diversity of 15 isolates of P. griseola from southern and eastern Africa into nine different races. Five of six isolates from Malawi and two of seven from Uganda, obtained from large-seeded Andean beans, were characterized into four different races considered Andean. These were compatible only or mostly with large-seeded Andean cultivars. The other eight isolates from Uganda, Malawi, and the Democratic Republic of Congo, obtained from a small- or medium-seeded Middle American beans, were characterized into five different Middle American races. These were compatible with Middle American and Andean cultivars. CAL 143 was resistant or intermediate under greenhouse conditions to all but one of the same 15 isolates from southern and eastern Africa, but it was susceptible to an isolate from Uganda obtained from a medium-seeded Middle American bean.

Bean seed dissemination systems in Malawi: a strategy.

ABSTRACT Farmers have shown considerable interest in purchasing seed of newly released dry bean (Phaseolus vulgaris L.) varieties in Malawi. However, this seed is not available on a large scale to farmers at present. The private seed sector in the country is not interested in bean seed production due to low profit margins. As a self-pollinating crop, once farmers have obtained initial seed stock, it can be recycled for some time. A strategy has been developed to focus on alternative sustainable informal seed production and dissemination systems, which builds on lessons learnt from previous experiences within Malawi and other African countries. These include: (i) informal seed multiplication, using smallholder farmers; (ii) informal seed distribution channels, using grocery shops, rural traders, extension agents, health clinics, and NGOs; and (iii) intensified variety promotion through publicity, using posters, leaflets, brochures and radio messages. These activities are carried out in close collaboration with farmers, NGOs, extension agencies, village traders and various other institutions. The results from initial sales through informal distribution channels were encouraging and 80% of the seed was sold.

Reduction in nutritional quality and growing area suitability of common bean under climate change induced drought stress in Africa

Climate change impacts on food security will involve negative impacts on crop yields, and potentially on the nutritional quality of staple crops. Common bean is the most important grain legume staple crop for human diets and nutrition worldwide. We demonstrate by crop modeling that the majority of current common bean growing areas in southeastern Africa will become unsuitable for bean cultivation by the year 2050. We further demonstrate reductions in yields of available common bean varieties in a field trial that is a climate analogue site for future predicted drought conditions. Little is known regarding the impact of climate change induced abiotic stresses on the nutritional quality of common beans. Our analysis of nutritional and antinutritional compounds reveals that iron levels in common bean grains are reduced under future climate-scenario relevant drought stress conditions. In contrast, the levels of protein, zinc, lead and phytic acid increase in the beans under such drought stress conditions. This indicates that under climate-change induced drought scenarios, future bean servings by 2050 will likely have lower nutritional quality, posing challenges for ongoing climate-proofing of bean production for yields, nutritional quality, human health, and food security.

Genomics, genetics and breeding of common bean in Africa: A review of tropical legume project

Abstract Common bean (Phaseolus vulgaris L.) is an important legume crop worldwide. The International Centre for Tropical Agriculture (CIAT) and its national partners in Africa aim to overcome production constraints of common bean and address the food, nutrition needs and market demands through development of multitrait bean varieties. Breeding is guided by principles of market‐driven approaches to develop client‐demanded varieties. Germplasm accessions from especially two sister species, P. coccineus and P. acutifolius, have been utilized as sources of resistance to major production constraints and interspecific lines deployed. Elucidation of plant mechanisms governing pest and disease resistance, abiotic stress tolerance and grain nutritional quality guides the selection methods used by the breeders. Molecular markers are used to select for resistance to key diseases and insect pests. Efforts have been made to utilize modern genomic tools to increase scale, efficiency, accuracy and speed of breeding. Through gender‐responsive participatory variety selection, market‐demanded varieties have been released in several African countries. These new bean varieties are a key component of sustainable food systems in the tropics.

Replication Data for: Using subsidised seed to catalyse demand-driven bean seed systems in Malawi

A six-step process in catalyzing and sustaining the PPP collaboration for producing and delivering improved bean seed was followed ; 1. Creating public awareness of released varieties. 2. Building partnerships to scale up supply. 3. Making basic seed of preferred varieties available to DAL and support services. 4. Scheduling activities around seed production, variety promotion, and seed distribution to a larger community for planting. 5. Participatory evaluation and performance tracking. 6. Generating and disseminating lessons learnt for scaling up. A follow up study was conducted in 2012 to assess farmers and actors along the bean seed supply chain satisfaction about the bean varieties and operations