Extra-Early Maturing Cassava Varieties: Breeding Status and Progress.

Late root bulking is a major factor leading to rejection and abandoning of improved cassava genotypes in sub-Saharan Africa. Extra-early bulking and high yielding (EB-HY) cassava varieties also referred to as extra-early maturing (EM) varieties in this review shorten the growth period from planting to harvesting and better fit into environments with short rainy season. Some EM cassava genotypes have been selected for different agro-ecological zones in Nigeria after evaluation for two seasons at three locations representing three agro-ecological zones in the cassava growing belt of the country. Molecular markers associated with EB-HY in cassava were also identified using Bulked Segregant Analysis (BSA). The selected EM cassava genotypes offer cassava growers high productivity in less than 12 MAP. This will reduce the problems associated with long dry season experienced in most parts of cassava growing areas as farmers can afford to harvest their cassava plants at the beginning of dry season in areas where rainy season lasts for about 6-7 months. Also, the molecular markers identified for EB-HY in cassava avail breeders the opportunity to select for EM genotypes at early stage of breeding programme and thereby reduce the cost of such breeding programme.