Relative Growth Rate and Net Assimilation Rate of Black Afara (Terminalia ivorensis) Seedlings Grown with Arbuscular Mycorrhizal Fungi (AMF) under NaCl Stress in Calabar, Nigeria

Aim: To ascertain how four distinct arbuscular mycorrhizal fungi (AMF) species affect the relative growth rate (RGR) and net assimilation rate (NAR) of Terminalia ivorensis under NaCl stress.

Study Location and Length: Calabar is situated in southern Nigeria. The study was carried out from February to May, 2022

Methodology: The field procedure was a 9x3x6 completely randomized design with nine treatments and three duplicates, which were further replicated six (6) times, totaling 162 pots. The Terminalia ivorensis young plants were induced using four different AM fungi species (Glomus mossae, Glomus intraradices, Glomus occultum and Glomus etunicatum) and predisposed to 75mM of NaCl stress. At six sequential harvests of 2, 4, 8, 10 and 12 weeks after emergence (WAE), dry biomass and AMF colonization were determined. relative growth rate and net assimilation rate were calculated using the dry weight data obtained at harvest (4,6,8,10 and 12 WAE).

Results: All the NaCl stressed young plants indisputably showed higher colonization of AMF in their roots than their unstressed replica. Young plants inoculated using Glomus intraradices (Gi) in fusion with NaCl (GiNaCl) had the maximum AMF root colonization of 98.35%, while 31.78% was the least in plants treated with G.occultum(Go) at 12 and 8 WAE, respectively. Plants treated with Glomus occultum revealed 0.46gg-1wk-1 as the highest RGR value and 0.22gg-1wk-1 was recorded in Gm, GmNaCl and GoNaCl as the least value at 12WAE. Furthermore, Glomus etunicatum treated plants recorded the maximum significant (p≤0.05) NAR of 0.55gg-1wk-1 and the least was 0.31gg-1wk-1 in seedlings inoculated with G.occultum under salt stress at 12 WAE.

Conclusion: The regeneration of afforestation and vegetation in Nigeria's coastal areas can be facilitated by inoculating with the right AMF, which can also increase the biomass production and accumulation of Terminalia ivorensis seedlings.