Forest Ecology and Management, 8 (1984) 221--228 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands 221 GROWTH AND ECTOMYCORRHIZAL DEVELOPMENT OF PINUS CARIBAEA SEEDLINGS INOCULATED WITH BASIDIOSPORES OF SCLERODERMA DICTYOSPORUM IN FERTILIZED NURSERY SOIL IN TANZANIA J.A. MAGHEMBE and J.F. REDHEAD* Division of Forestry, University of Dares Salaam, P.O. Box 3009, Morogoro (Tanzania) *Present address: The Coach House, Chilbolton, Stockbridge, Hants. S020 6AZ, Great Britain (Accepted 5 January 1984) ABSTRACT Maghembe, J.A. and Redhead, J.F., 1984. Growth and ectomycorrhizal development of Pinus caribaea seedlings inoculated with basidiospores of Scleroderma dictyosporum in fertilized nursery soil in Tanzania. For. Ecol. Manage., 8: 211--228. Seeds of Pinus caribaea were sown in plastic pots containing nursery soil with or without a basidiospore inoculum of Scleroderma dictyosporum. After seedling establish- ment, five fertilizer treatments involving 0, 250, 500, 750 and 1000 g NPK per m 3 of nursery soil were administered. The ratio of N:P:K in NPK was 3:3:1. Basidiospores of S. dictyosporum were an effective inoculum for P. caribaea seed- lings. Inoculated seedlings showed superior growth in height, root collar area, length of stem with needles and dry matter production. Inoculation also increased the con- centration of P in the plant tissues but had no effect on other nutrients studied. Fertilizer response was evident, but there were generally no benefits of using fertilizer levels above 250 g NPK per m~Boil. In fact, myeorrhizal developmefit was progressive- ly reduced with each increase in the level of NPK fertilizer. Tissue Mg concentrations were also deficient, a reflection of nutrient uptake imbalance due to high concentra- tions of ammonium sulphate and potassium chloride in the soil. Basidiospores of S. dictyosporum can therefore be used for routine inoculation of P. caribaea seedlings in nursery soils at low levels of NPK. Coincidentally such a reduction in the amount of NPK applied in nursery soil will have both biological as well as economic benefits. INTRODUCTION Techniques for ectomycorrhizal inoculation in forest nurseries have been reviewed recently by Marx (1980) and by Trappe (1977). Traditionally, soils containing ectomycorrhizal fungi propagules have been used to inocu- late nurseries in new afforestation sites (Mikola, 1973). This method is preferred especially in the tropics, because it is easy to apply. However, soil inoculum is bulky, can introduce pests and pathogens into nurseries 0378-1127/84/$03.00 © 1984 Elsevier Science Publishers B.V.