INHERITANCE OF DROUGHT TOLERANCE TRAITS IN ANDEAN X ANDEAN AND ANDEAN X MESOAMERICAN F2 POPULATIONS

摘要

Common bean is an important food and cash crop in Zimbabwe and other parts of Eastern and Southern Africa that is mainly grown by small-scale farmers for whom it is a major protein source for the human diet. Of late, common bean is also recognized tobe a good source of essential micronutrients. The average per capita bean consumption across Africa in 2001 was 2.7 kg per year, with high-end consumption at 27.7 kg per year in Rwanda (FAO, 2003). Despite its importance in nutrition and income generation, common bean production is often threatened by drought episodes. In addition, for many countries such as Zimbabwe, the area under common bean is expanding into semi-arid areas suppressing average national production, which for Zimbabwe remains low at 500kg/ha even as total production increases due to greater total hectarage devoted to the crop. The chief cause of this low productivity is drought. Drought management through supplementary irrigation and good agronomic practices (mulching, tie ridging etc) has been of little use with small-scale fanners due to a number of factors, especially the high cost of irrigation equipment and monthly water charges. Genetic improvement of commercially grown cultivars for drought tolerance is the only cheap and viable option for small-scale farmers of Zimbabwe. This study is aimed at understanding the mode of inheritance of drought tolerance from Andean and Mesoamerican sources crossed with common bean cultivars important to Zimbabwe and will form the basis for developing drought tolerant bean varieties for the farming community.