Assessment of Agro-morphological Parameters of Two Accessions of Undergrowth Yam (Dioscorea sp.) Cultivated in the Inter-rows of Mature Rubber Trees (Hevea brasiliensis) in Daloa, Côte d’Ivoire

The valorization of mature rubber tree inter-rows by food crops could solve the problem of food insecurity in rubber tree-growing areas. This study aims to assess the agro-morphological parameters of understory yams sown under mature rubber trees. To this end, a trial was carried out in Daloa on a mature rubber tree plantation and a control plot of sole yam. Two accessions of undergrowth yams, “Bacoué” and “Soupkataloa”, were grown in the rubber tree inter-rows and monoculture. The experimental design was a completely randomized block with 15 repetitions. The parameters measured on the yams were emergence rate, specific leaf area (SLA), number of days to emergence, number of days to first leaf, stem height (Ht), crown diameter (CD) and production. The results showed that the accessions tested under rubber trees emerged relatively well, with 66.67% and 70.83% rates for Bacoué and Soupkataloa, respectively. These combined accessions also showed the largest SLAs of 343 cm2/g for Bacoué and 328.5 cm2/g for Soupkataloa during the dry season. However, emergence was late under the rubber trees compared with the yam monoculture. Bacoué emerged 179.19 d after sowing and had its first leaves 42.88 d later, whereas these values were 58.18 d and 11.71 d respectively for Soupkataloa. However, although Bacoué performed better, with an Ht of 825 cm in 70 days and a large CD (11.18 mm), its production was identical to that of Soupkataloa. These results show that undergrowth yams can be combined with mature rubber trees to guarantee food security.