Effect of Mycorrhizal Fungi on the Growth and Nutrient Status of Slash and Radiata Pine Seedlings

Abstract

Slash pine (Pinus elliottii var. elliottii Little and Dorman) and radiata pine (P. radiata D.Don) were inoculated with pure cultures of fungi isolated from mycorrhizas of mature pine. All eight species tested, except a Rhizopogon sp. obtained from slash pine, formed mycorrhizas with radiata pine, and all except two unidentified fungi from radiata produced mycorrhizas on slash. The effects of inoculation on yield and nutrient uptake were determined four months after seedlings were transplanted to a sterile peat-sand mixture previously steeped in nutrient solution. Inoculation gave better growth and improved nutrient status even where it did not result in mycorrhiza formation. Unidentified fungi were more effective than Rhizopogon roseolus or Suillus granulatus. Pine seedlings of any one species derived most benefit from inoculation with fungi isolated from that species. The results are discussed in relation to the problems of introducing pure cultures of mycorrhizal fungi into natural soils.