Mycorrhizal Status of Natural Stands of Pterocarpus erinaceus Poir. (Fabaceae) in Sudanian and Guinean Zones of West Africa

Abstract

Background and Aims: The sylviculture of Pterocarpus erinaceus is still in its infancy due to lack of information on its biology. The aim of this study is to investigate its mycorrhizal status in order to better address its sylviculture. Place and Duration of Study: The study was performed on the field from May 2019 to December 2020 and data were analyzed at the laboratory from January to March 2021. Methodology: The frequency and intensity of mycorrhization were determined under a microscope after staining with trypan blue of fine roots collected at a depth of 20 cm under adult plants at 5 sites, 3 in the Guinean zone and 2 in the Sudanian zone in Togo. The spore density was obtained on soil samples taken at the same depth under the same trees. Results: Results indicate, without significant differences (P value = 0.166) among sites, and show that P. erinaceus is frequently mycorrhized (88% to 94%). However, there were significant differences (P value = 0.001) in spore densities between sites located in the Sudanian zone (16.53 ± 1.25 and 10.66 ± 0.71 spores per gram of soil – SPGS – respectively for the Fazao-Malfakassa and Oti-Kéran-Mandouri) and those located in the Guinean zone (4.54 ± 0.3, 2.93 ± 0.43 and 3.76 ± 1.01 SPGS respectively at Abdoulaye, Hahomegbe and Togodo). There are significant differences between mycorrhization intensities Togodo which has a mycorhization intensity of 33.52 ± 2.54   and other sites. The redundancy analysis carried out by taking into account substrates’  chemical characteristics shows that spore density remains low when phosphorus and nitrogen are important in the rhizosphere whereas the intensity of mycorhizations is low when PHKCl is high. Conclusion: This study provided evidence of mycorrhizal symbiosis in Pterocarpus erinaceus whether in the Sudanian or Guinean zone. Chemical quality of the growing substrate has an influence on parameters of mychorization. Further studies should therefore allow an assessment of the degree of dependence of this species with respect to the possible benefits associated with this symbiosis.