Phosphorus nutrition of ectomycorrhizal Gnetum africanum plantlets from Cameroon

Abstract

A study was carried out to evaluate the effect of mycorrhization on the growth and P uptake of Gnetum africanum rooted cuttings at low and high inorganic phosphorus availability. Gnetum rooted cuttings were grown in a peat/sand 50:50 mix to enable the development of fine roots. Nutrient evaluation was carried out in sand/peat 10:1 mix (NIL), mix amended with 30 mg/kg P (I), mix amended with 300 mg/kg P (II). Generally ectomycorrhizal plants showed better growth than non-mycorrhizal plants. The number of new EM tips formed decreased with an increase in P level. Ectomycorrhization led to an increase in shoot dry weight, number of leaves and shoot elongation. Ectomycorrhization of Gnetum also resulted to increased access to added P whilst the effect on N uptake was greatest when P was added. The results showed that Gnetum responds positively to mycorrhization and that the response may not be solely attributed to increased uptake of nutrients including P and N. From this observation it is certain that in the domestication of Gnetum, mycorrhization alone would not be enough but that a combination of mycorrhization and nutrient addition would be necessary for the successful establishment and growth of the plant.