Effect of Treatments on Seed Germination of Ricinodendron heudelotii (Euphorbiaceae) in a Nursery in Soubré (South-West Côte d’Ivoire)

Abstract

Ricinodendron heudelotii , commonly known as Apki in Côte d’Ivoire, is a multi-purpose tree. However, threatened by climatic variations and anthropogenic activities, in particular the extension of agriculture and the high human consumption of its seeds, the species has difficulties in natural regeneration due to the integumentary resistance of the seeds. The objective of the study is to contribute to the improvement of the germination potential of Ricinodendron heudelotii in nurseries with a view to sustainable agroforestry and thus its domestication. During this study, carried out in the department of Soubré, Apki seeds were tested by 14 treatments, including the control treatment, before sowing. They are grouped into 5 processes, namely: mechanical (scarification), chemical (soaking with sulphuric acid for various periods of time), immersion in water for various durations, hormonal (soaking with gibberellin in different concentrations), and thermal (soaking in boiling water). The results showed that seed treatments by scarification (T 1 ), soaking in tap water for 7 days (T 12 ), and soaking with sulphuric acid for 12 minutes (T 10 ) gave the best germination rates with 51.66%, 43.33%, and 30% respectively, within a short delay of 10 to 13 days, during a maximum germination period of 11 days. This study contributes to the acquisition of Apki seedlings at a reduced cost and in a better timeframe for their integration into agroforestry for sustainable conservation. Thus, without costs and being less laborious, with a germination rate of 43.33%, the method of soaking in water for 7 days is recommended for farmers for the production of seedlings of the species for its domestication, unlike scarification which is labor-intensive and presents risks of seed destruction.