Relationship between plant growth and organic acid exudates from ectomycorrhizal and non-ectomycorrhizal <i>Pinus patula</i>

Abstract

Plant–mycorrhizal interaction is an important association in the ecosystem with significant impacts on the physical, biological and chemical properties of the soil. In the present study, potential relationships that exist between organic acid production by ectomycorrhizal pine seedlings and plant parameters in the absence of any significant environmental stress were investigated. The aim of the study was to investigate the contribution of organic acid production to plant growth. Four different ectomycorrhizal fungi were used in a mycorrhizal synthesis experiment to colonise roots of Pinus patula. Ectomycorrhizal and non-ectomycorrhizal plants were used in a pot trial experiment that lasted for 24 weeks. After harvesting, plant materials as well as soil samples underwent different analyses, which included the determination of pH, organic acids, plant biomass, and foliar and root phosphorus and potassium. The results indicated a significant interaction (P < 0.0001) between fungal type and organic acid production. This reflects the influence of fungal type on organic acid production. However, it was observed that organic acids secreted into the soil are not directly linked with the quantity of nutrients detected in either the root or shoot, but seemed to positively influence plant growth as reflected in the result from root and shoot biomass.

Keywords: ectomycorrhizal fungi, nutrients, organic acid, phosphorus, pine, potassium