Selection of Efficient VA Mycorrhizal Fungi for Trifoliate Orange

Trifoliate orange (Poncirus trifoliata) is an important citrus rootstock but it has a slow growth rate. Eighteen different mycorrhizal fungi were screened for their symbiotic response with Trifoliate orange. Of the 18 fungi, G. velum (Nedlands), G. caledonicum (Nedlands), G. merredum (Nedlands), G. macrocarpum (Ruakuara) and Acaulospora sp. (ICRISAT) were found to be the best for improving growth and nutrition resulting in greater plant height, stem diameter, plant biomass, P, Zn and Cu content. All the five fungi selected were statistically equivalent in improving growth and nutrition of Trifoliate orange. Inoculation of the root stock with these fungi induced a stem girth of pencil thickness, i.e. ready for budding in 14–15 months in contrast to 22–24 months without mycorrhizal inoculations, thus saving about 8–9 months.