Germplasm evaluation for climate adaptation and drought tolerance: The cases of local varieties of maize in Zambia and cowpea in Botswana

Water shortages as a result of changes in rainfall patterns and increases in temperatures are associated with climate change.Rising temperatures and evaporation rates exacerbate water scarcity problems primarily aff ecting dry-land crop production systems in southern Africa.Thus, the search for drought-tolerant crop varieties becomes necessary to mitigate climate change and to achieve food security in the region.Fifty maize germplasm accessions obtained from the Zambian gene bank were characterized at Mount Makulu Research Station in Zambia to identify suitable varieties for on-farm evaluation.In that regard, data was collected on days to 50% tasselling, days to silking, plant height, ear height, number of leaves above leaf ear, tillering index, tassel type, number of kernel rows, kernel type, and kernel colour.Furthermore, we carried out on-farm participatory evaluation of 20 local varieties of maize at two representative sites.Farmers selected six crop varieties on the basis of their early maturity, high yielding ability, drought tolerance, and tolerance to fi eld pests and diseases.The selected maize varieties are suitable for large-scale production or variety development for the targeted sites or areas with similar agro-ecological conditions.In Botswana, greenhouse and fi eld studies were conducted to characterise 20 cowpea genotypes based on diff erent drought tolerance indices.Results showed that stress tolerance index (STI) and drought resistance index (DI) were the most suitable indices for selecting cowpea genotypes for drought tolerance.Six cowpea collections were tested in a fi eld study at Hukuntsi, situated in the Kalahari Desert, in 2014-15.Analysis of variance and regression analysis showed that three accessions [BCA001 (Blackeye), BCA009 (Mahutohuto), BCA016 (Speckled brown] were promising drought-tolerant varieties displaying a higher plant drought survival (PDS%) rate under fi eld conditions.Signifi cant correlations were detected between PDS% and STI, indicating the usefulness of the two parameters in selecting drought-tolerant cowpea genotypes.The two selected cowpea genotypes are recommended for cultivar development or production under drought-prone and rain-fed farming systems in southern Africa.Resumo: A escassez de água, resultante das alterações nos padrões de precipitação e do aumento da temperatura, está associada às alterações climáticas.O aumento da temperatura e das taxas de evaporação exacerbam os problemas de escassez de água, principalmente nos sistemas de