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Effect of the seeds provenance and treatment on the germination rate and plants growth of four forest trees species of Côte d'Ivoire

Akaffou D.S., Kouassi Kouame A., Bi Boh Gore N., Yao Abessika G., Kouadio Kouassi H., Hamon P., Sabatier S.A., Duminil J.. 2021. Journal of Forestry Research, 32 : p. 161-169.

DOI: 10.1007/s11676-019-01064-y

The rapid rate of deforestation in Côte d'Ivoire has led to loss of plant species diversity and also threatens some commercial tree species with extinction. Some reforestation and afforestation has been completed. However, for some species, the numbers of surviving transplants has declined. Hence, it is necessary to develop properly adapted and resilient genotypes that can effectively support the programs of forest restoration. In this context we evaluated the effects of the provenances of seeds and of various treatments on the germination rates and on plant growth of four commercial trees species (Pycnanthus angolensis, Terminalia superba, Mansonia altissima and Pterygota macrocarpa). We analyzed these parameters for seeds of three provenances (Daloa, Akoupé and Daoukro) of four species and for thirty plants aged 6 months per provenance. Time to begin germination and time to reach maximum germination were similar among species, and were not influenced by either treatment or provenance. Untreated seeds and those soaked for 24 and 48 h in water at room temperature yielded the highest germination rates, irrespective of species or provenance. The one exception was P. angolensis, for which no germination was recorded. Within species, some provenances produced higher germination percentages than did others. No clear relationship was computed between the germination rate and the morphometric characteristics of the seeds which varied significantly between provenances. Plant growth and morphological variability also depended greatly on provenance. Genetic factors might be implicated, therefore provenance trials should be undertaken and evaluated. Furthermore, molecular analysis should be undertaken to confirm the implications of genetic factors and allow for genetic selection.

Mots-clés : traitement des semences; provenance; faculté germinative des semences; croissance; arbre forestier; santé des forêts; santé des plantes; terminalia superba; mansonia altissima; côte d'ivoire; pycnanthus angolensis; pterygota macrocarpa

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