Impact of Jatropha curcas L. on Vesicular-Arbuscular Mycorrhizal (VAM) Fungi in Various Plantation Systems

Abstract

The study determined the impact of Jatropha curcas L. on vesicular-arbuscular mycorrhizal (VAM) fungi. Soil samples were obtained from various plantation systems (Pila, Fort Magsaysay, Nakar, Real, UP Land Grant, and Quirino), while root samples were obtained from a six-month old J. curcas L. plantation in Tranca. The soils were used for the determination of VAM fungi spore density, while roots were evaluated for the presence or absence of root colonization by VAM fungi. For each site, soil samples consisted of: rhizosphere samples of mature J. curcas L. (J+) and soils not planted with J. curcas L. (J-). The spores from each soil sample were obtained using the wet-sieving method, and were estimated per 100 gram soil dry weight using an improvised Petri dish. VAM fungi in soil were identified using spore-based taxonomy up to genus level and the abundance of each genus was noted for each soil sample. For evaluation of the presence or absence of root colonization, root samples were cleared using 10% KOH, acidified using 5% HC1, stained using Lactic acid tryphan blue, and destained using glycerol lactic acid. For statistical analysis, t-test with the level of significance (a) 0.10 was used. Results showed that spore densities in J+ were either significantly higher or have no significant difference with those obtained in J-. hi addition, Glomus sp. and Acaulospora spcwere more abundant in J+ than in J-. Fifty-eight (58%) of the root samples showed positive for colonization by VAM fungi. This study showed that J. curcas L. does not exude fungicidal compounds that can reduce the abundance of VAM fungi in soil. This study also showed that J. curcas L. does not inhibit the colonization of its roots by VAM fungi.