Stability and genotype by environment interaction of provitamin A carotenoid and dry matter content in cassava in Uganda

Efforts are underway to develop staple crops with improved levels of provitamin A carotenoids to help combat dietary vitamin A deficiency (VAD), which has afflicted the health of resource-poor people in the developing world. As a staple crop for more than 500 million people in sub-Saharan Africa, cassava enriched with provitamin A carotenoids could have a widespread nutritional impact. To this effect, 13 provitamin A clones were evaluated in a randomized complete block design in six environments to assess genotype by environment interaction (GEI) effects for total carotenoid (TCC) and dry matter content (DMC) in roots. Additive main effect and multiplicative interaction analysis showed significant variation among genotypes for TCC, DMC, fresh root weight and harvest index. Environmental effects were non-significant for TCC, but GEI effects were significantly large for all traits measured. There were significant temporal increments for all traits measured within 12 months after planting. TCC correlated negatively with DMC, illustrating an important challenge to overcome when developing provitamin A cassava varieties without compromising DMC, which is a major farmer-preference trait. Nonetheless, best performing genotypes were identified for TCC, DMC and FRW, and these could constitute genetic resources for advancement or developing breeding populations through hybridization.