Development of Dual-purpose Sweetpotato Varieties through Participatory Breeding in Rwanda

Sweetpotato forms a major part of the diet of both rural and urban communities in Rwanda. Moreover, it is expected that the crop could become more important than it is already now, especially for farmers operating in mixed crop-livestock systems. The interest in sweetpotato as an animal feed is associated with the implementation of a policy regarding zero grazing practices as one of the ways to reduce soil erosion. This research was conducted to develop dual-purpose sweetpotato varieties through a participatory approach, using an accelerated breeding scheme. Sixty parents comprising local cultivars and introduced germplasm were used in a crossing block to generate true seeds. In total, 5380 well-established genotypes were selected from the seedling nursery and planted in an observational trial at Rubona, Karama and Ngoma, during 2011 season B (season A is the first rainy season and season B the second rainy season). Participatory evaluation and selection was conducted by 42 people, with 25 females among them and 268, 25 and 10 best clones were selected from an observational trial, preliminary and advanced trials, respectively. Selection of dual-purpose clones was based on the range of the ratio of roots to vines in terms of dry matter yields, where a clone with a range of 1.5-2.0 was classified as a dual-purpose clone. The best performing clone for root yield in 2012 season B was RW11-17, with a mean yield of 28.1 t/ha, followed by RW11-3736 with a yield of 27.5 t/ha. Clones RW11-1860 and RW11-4923 were high in root dry matter content (DMC), at 37.8% and 37.5%, respectively, whereas RW11-1860 ranked the first in vine DMC with a mean of 20.7%. In taste tests, two white-fleshed genotypes RW11-1860 and RW11-17 were ranked best by farmers, whereas clone RW11-2910 was ranked first among the orange-fleshed varieties. Six of the best performing clones, namely RW11-17, RW11-1860, RW11-2419, RW11-4923, RW11-2560 and RW11-2910, had a ratio root/vine ranging between 1.5 and 2.0, and were therefore considered as dual-purpose-use clones. These performing clones were officially released in February 2013.