Synergistic Effects of Dual Inoculation with Rhizobia and Arbuscular Mycorrhizal Fungi Selected on Peanut Seedlings Growth Parameters

Abstract

Plant inoculation with selected microorganisms remains a good alternative environment friendly. It minimizes the excessive use of chemicals fertilizers and increases the yield. The aim of the present study is to evaluate the effect of dual inoculation with arbuscular mycorrhizal fungi (AMF) and rhizobia selected on growth parameters of peanut seedlings, in greenhouse conditions. The experiment was conducted in a greenhouse (5°23 N to 4°0 W) located at the University Nangui Abrogoua (UNA) in Abidjan, Côte d’Ivoire during three months. Peanut seeds were sown into plastic bags containing 1 kg of non-sterile substrate. The fungal inoculum was added at sowing and after 5 days of crop, 5 mL of bacterial suspension was added around the rootlet. Plants were watered regularly and their height was measured every two weeks. After three months of crop, plants were harvested ; plant growth, mycorrhizal and nodulation parameters were measured. Nodules were detached, counted, and weighted per plant. The aerial and root weights were determined after drying each compartment. Then, the mycorrhization parameters were determined after staining the roots. Results show better growth of inoculated plants compared to non-inoculated plants. Indeed, dual inoculation with both AMF and rhizobia has significantly improved yield paramaters such as the number and weight of pods and nodules number. Significant increase in pods number from 1,44±0,53 to 2,33±0,87 (α = 0.05) was observed. Pods weight was significantly increased from 2,15 ±0,73 to 4,09±0,76 g by dual inoculation. As for nodules number, a significant increase from 72,33±7,47 to 87,20±9,78 (α = 0.05) was also observed. These results confirm once again stimulatory effects of these symbionts, described by several authors. Indeed, positive effects of single inoculation with rhizobia or AMF and dual inoculation with both have been widely demonstrated on many plant species.