Drought resistance of selected forage legumes for smallholder farmers in East Africa

To improve feed availability for smallholder farmers in East Africa, we investigated the biomass production and drought resistance of five forage legumes in semi-arid environments of Rwanda and Uganda. The crops were grown under rain-fed conditions (control) and with additional irrigation (irrigated) and harvested at two-monthly intervals four to five times. Before harvests, the youngest leaves of the crops were sampled for stable carbon isotope analysis for an indication of intrinsic water-use efficiency. This is the first time carbon isotope data is reported for these species. The total annual dry matter production was larger for the legumes grown in Uganda than in Rwanda. However, there were large differences among harvests, with the variability between smallest and largest harvests being similar for both countries. Carbon isotopic signatures were more enriched for samples from Rwanda, hinting at a larger intrinsic water-use efficiency under the local conditions. Canavalia brasiliensis had most enriched carbon signatures in both countries, coupled with acceptable biomass production and should be further investigated for adaptation in smallholder farming systems.