Combining ability analysis of cassava (Manihot esculenta Crantz) genotypes for cassava mosaic disease in Zambia

Abstract

Despite the importance of cassava as a staple crop in Luapula province and other regions of Zambia, there is a lack of information on the resistance to diseases and associated combining ability of the locally cultivated cassava cultivars. Therefore, this study was carried out in 2010/2011 to: identify progeny with resistance to cassava mosaic disease (CMD); evaluate the performance of F1 progeny for agronomic traits and determine general combining ability and specific combining ability for resistance to CMD. A total of 809 genotypes comprising of parents and progeny were developed through controlled crossing and evaluated using a-lattice design. The general combining ability (GCA) and SCA mean squares (MS) were highly significant (P<0.001) for CMD. The total sum of squares (SS) for CMD was mainly accounted for by specific combining ability (SCA) effects (67.9%). Bangweulu a local highly susceptible cultivar had the most negative, significant (P<0.001) GCA effect among the landraces. In summary, the results indicated that the local landraces (Bangweulu and Kampolombo) used as parents can be sources of CMD resistance.