African Yam Bean (Sphenostylis stenocarpa) Nodulates Promiscuously with Rhizobium Indigenous to Soils of Botswana.

Abstract

African yam bean is a versatile legume crop, relished for its protein rich tubers, seeds and leaves which are utilized as spinach. It is a highly adaptable crop capable of producing growth even on acid and highly leached sandy soils. A pot experiment was conducted at Botswana College Agriculture to determine nodulation of African Yam Bean with Rhizobium indigenous to soils of Botswana. Soil collected from two different sites at Botswana College of Agriculture were used with each planted with African Yam Bean and cowpea plants. No fertilizer supplementation was added to the soils. Data was collected after eight weeks of establishment. The parameters measured were the number of nodules, nodule weight and plant weight. The data was analysed using Genstat software Discovery Version. African Yam Bean formed nitrogen fixing nodules under the soils from the two different sites. It compared favorably with cowpea because there were no significant differences in nodulation (nodule number and nodule weight, fresh and dry weight) between the two species. This study has further revealed that African Yam Bean is adaptable to a wide variety of environments and could be successfully grown in Botswana without expensive inputs such as inorganic fertilizers.