Mycorrhizal inoculation enhances growth and nutrient uptake of micropropagated apple rootstocks during weaning in commercial substrates of high nutrient availability

Apple (Malus pumila L.) plants of the rootstock clone MM106 were micropropagated from axillary buds and, after rooting, were transplanted into pots containing three different commercial-type peat-based substrates, fertilized before planting with about 100 mg soluble P per liter (about 300 mg kg(-1) wet substrate). Plants were inoculated at transplant with the arbuscular mycorrhizal fungus Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe. After 112 days of growth, roots were heavily colonized by mycorrhizal fungi. Inoculation increased P uptake in all substrates. Plant growth was enhanced by inoculation in two of the substrates. During the growth period, the P content of the substrate was severely depleted, and this may explain the intense root colonization and nutrient uptake enhancement observed in such nutrient-rich substrates. (C) 2000 Elsevier Science B.V. All rights reserved.