Eucalyptus Field Growth and Colonization of Clones Pre-Inoculated with Ectomycorrhizal Fungi

Abstract

Ectomycorrhizae are classified as biotechnology to increase the sustainability of planted forests, and fieldwork is needed to confirm its effectiveness. The growth of rooted cuttings of Eucalyptus clones GG100 and GG680, which had been previously inoculated in the nursery with ectomycorrhizal fungi, was evaluated after planting them in the field. The ectomycorrhizal fungi (EMF) inoculated were: Pisolithus microcarpus, Hysterangium gardneri, or Scleroderma areolatum. Uninoculated rooted cuttings were used as controls. The inoculated treatments and the uninoculated controls (low P control) were grown in a nursery with reduced phosphate fertilization. Additionally, uninoculated controls were grown on a substrate with complete phosphate nursery fertilization (high P control). After two months, the plant height of clone GG100 inoculated with P. microcarpus was 16% taller and of clone GG680 13% higher than the low P control treatment. At the same time, the collar diameter of the plants inoculated with H. gardneri and P. microcarpus was the same as in the high P control. At 12 months, the growth of the inoculated and low P control plants was the same as in the high P control. For ectomycorrhizal colonization, after six months, the mean percentage of colonized root tips was highest in plants inoculated with S. areolatum, followed by those inoculated with P. microcarpus and of the low P control. After one year, ECM colonization was equal in all treatments and 4.3 times greater than it was at 6 months. Inoculation with ECM fungi in the nursery boosts early plant growth after transfer to the field, although the effect depends on the specific ectomycorrhizal fungus and the clone. Further ectomycorrhizal colonization of Eucalyptus occurs naturally and increases with tree development in the field.