ASSESSMENT OF ECTOMYCORRHIZAL FUNGI MORPHOLOGY ON SEEDLINGS OF SHOREA LEPIDOTA AND S. LEPROSULA IN ELEVATED, CONTROLLED CARBON DIOXIDE ENVIRONMENT

Abstract

In response to rising atmospheric carbon dioxide (CO₂) levels, the dynamics of Dipterocarpaceae, a crucial tree family member, has undergone significant changes that influences the associated soil microorganisms including ectomycorrhizal (ECM) fungi. This study aimed to characterise ECM fungi morphologically, focusing on Dipterocarpaceae seedlings exposed to elevated CO₂ condition, by utilising morphotyping techniques. Root samples from Shorea leprosula and S. lepidota seedlings, each with three replicates, were collected from the Open Roof Ventilation System (ORVS) at the Universiti Kebangsaan Malaysia (UKM). The ECM-infected roots were isolated under a microscope and images of ECM morphotypes were captured and recorded for identification. A total of 13 ECM morphotypes were documented across both Dipterocarpaceae species. Eleven morphotypes were observed on S. lepidota seedlings, with six identifiable up to the genus level encompassing the genera Russula and Lactarius. Whilst, only two morphotypes on S. leprosula seedlings remained unidentifiable. Significant differences in root characteristics were observed between S. lepidota and S. leprosula seedlings, with the latter exhibiting larger, taller, and longer roots. The largest surface area was recorded in S. leprosula seedlings (19.2 cm2), accompanied by a higher number of root tips (482 tips) compared to S. lepidota (233 tips). These observations highlighted the differences in root architecture between the two species that may influence mycorrhizal associations. This underscores the distinct root morphologies between the two Shorea species. In conclusion, subsequent research is imperative to ascertain the species of these ECM morphotypes to ensure the sustainability of Dipterocarpaceae species.