Mycorrhizal Responses of Radiata Pine in Experiments with Different Fungi

Abstract

In glasshouse and field studies large differences occurred between different mycorrhizal fungi in their stimulation of radiata pine (Pinns radiata D.Don) growth. In the glasshouse, significant differences in this also occurred between strains of Rhizopogon luteolus Fr. and Nordh. R. luteolus and Suillus granulatus (L. ex Fr.) O. Kuntze usually gave good stimulation but S. Intens (L. ex Fr.) S. F. Gray was usually poor. Field responses to inoculation were obtained within 200 m of an existing plantation of radiata pine at a site where naturally occurring mycorrhizal fungi were present. Growth rates of inoculated plants were greater than those of uninoculated plants for the first 32 months after which growth rates were the same, height differences at that time being maintained. When growth rates of inoculated and uninoculated trees became the same all plants in uninoculated plots were dark green and had become mycorrhizal. Increased seedling survival during the dry summer following planting occurred with plants inoculated with R. luteolus and S. granulatus due to increased plant vigor. In a second field experiment where a high population of an efficient type of mycorrhizal fungus occurred naturally, little growth response resulted from inoculation.