Bridging tradition and technology: comparing growth performances of grafted and tissue cultured RRIM600 Hevea brasiliensis trees in West African plantations

Abstract The global demand for natural rubber emphasizes the need for increasing yield per hectare as the expansion of planting areas becomes difficult. To overcome some of the limitations related to the propagation of rubber trees through grafting, research has been carried out for years on Hevea clonal plants produced by in vitro tissue culture technology (vitroplants, VP). This study conducts a large-scale evaluation of VP across two rubber estates in Ivory Coast and Ghana. Using VP could significantly reduce the growth time of seedlings in the nursery and provide flexibility in planting schedules independent of seed availability. For 66 months, 14 ha of field trials were monitored to compare growth dynamics, stand uniformity, and trunk conicity of VP with trees from grafted plants (GP) of RRIM600 clone. The findings reveal that VP exhibited superior trunk girth at 66 months, suggesting an earlier readiness for tapping compared to GP with a more conical trunk shape, which may lead to increased latex yield. The differences in growth rates in the field between VP and GP were significantly affected by the developmental stage of the plants at planting, with VP being planted with fully developed leaves and self-rooted systems, while GP were planted with developed rootstocks but dormant buds. This enabled VP to establish more rapidly and thus reach readiness for latex tapping sooner than GP. The study underscores the importance of further research on clonal selection, acclimatization period, rootstock interactions and the yield performances of this novel planting material.