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Evaluation for High Iron and Zinc Content among Selected Climbing Bean Genotypes in Rwanda

Mukamuhirwa F and Rurangwa E

Daily consumption of beans in Rwanda may offer the opportunity for alleviating micronutrient malnutrition since other sources of these elements are expensive and/ or unavailable. In light of improving the nutritional status of many Rwandans, identification of new bean varieties able to accumulate high Fe/Zn content in addition to high yield performance would be good news for the country. The objective of this study was to identify and select climbing bean genotypes that have high mean yield, iron and or zinc content that should be the candidates for release for the traits of interest. Trials of seven climbing bean genotypes were conducted in ten research centers of Rwanda Agriculture Board (RAB) in 2017A and 2017B cropping seasons in randomized complete block design with 3 replications. Grain yield differed significantly (P ≤ 0.001) among the seven climbing bean genotypes evaluated and environments. Strong interactions between genotype and environment were observed (P ≤ 0.001) for yield, iron and zinc content. Grain yield averaged over the two seasons varied from 554 to 4,906 kg ha^-1. The least grain yield was achieved with RWV 2365-2 in Ngoma while greater yield was achieved with RWV 2350-2B in Muhoza. The across environments means revealed that Nyiramagorori had the least grain yield (1966 kg ha^-1) while MBC 71 had greater yield (2,502 kg ha^-1). Mean iron and zinc content in seeds differed significantly (P ≤ 0.001) among the seven climbing bean genotypes and ten environments. The mean iron content varied between 54.0 and 91.7 ppm. The genotype 665SI-4/1 averaged a low iron content of 63.0 ppm while 665SI-4/1 averaged a greater iron content of 76.4 ppm. In general three climbing bean genotypes among the seven evaluated showed superior performance for the three traits evaluated (yield, iron and zinc content) across environments. These genotypes include Rwibarura, RWV 2350-2B and MBC71.