On-farm phenotypic evaluation and stability analysis of provitamin A cassava (Manihot esculenta) varieties for agronomic traits, stress tolerance and tuber yield across Kwara state, Nigeria

Cassava ( Manihot esculenta ) is a food security crop in many parts of Africa including Nigeria. Heavy reliance on cassava for food results in malnutrition because it lacks micronutrients such as vitamin A. Provitamin A cassava varieties have the potential to sustainably reverse this trend. More recently, efforts to release provitamin A cassava varieties have intensified. Therefore, there is need to compare the best available white fleshed cassava with provitamin A varieties and assess their stability using GGE biplots. Two provitamin A varieties namely, TMS 1368 and TMS 07/0593, as well as one local variety (TME 419), were laid out in randomized complete block design in three replicates, at three locations across Kwara state. Data collected were subjected to ANOVA and GGE biplots. The results showed that high genetic variation existed among the cassava varieties for fresh tuber weight, carotene content, plant height, number of stems and tubers, as well as pest and disease severity. This implies that there is room for improvement. TMS 1368 was better yielding and adaptable than TMS 07/0593 and compared favourably with TME 419. GGE biplot was very useful in selecting a broadly adapted variety, a specific variety for target environments and delineating the environments into two mega environments. In improving carotene content of provitamin A cassava, caution should be taken not to have a negative impact on fresh tuber weight and dry matter content. TMS 1368 was the most suitable of the tested cassava varieties that is capable of addressing food security and vitamin A deficiency adequately. Therefore, it should be recommended to farmers for cultivation and consumption in order to improve vitamin A deficiency and enhance food and nutrition security.