Long-term effects of nursery starter substrate and AM inoculation of micropropagated peach x almond hybrid rootstock GF677

The peach x almond hybrid GF677 was inoculated in three different substrate s: sandy soil, peat and a commercial peat-bark compost mix, immediately aft er the weaning stage. After 3 months of growth under greenhouse conditions, plants were transplanted in a microplot set-up. At transplanting, differen ces in growth and in mycorrhizal colonisation were significantly related to the starter substrate used; plants grown in peat were taller than plants g rown in soil or in the compost-peat mix. Although both soil-less growing me dia were less conducive than soil to AM colonisation, the compost-pear mix resulted in higher colonisation percentages. At the end of the first growin g season, there were significant interactions between starter substrate and inoculation treatments affecting plant growth. After two growing seasons, the level of AM root colonisation was similar for all inoculated plants, an d all plants presenting the symbiosis were bigger than those that had not b een inoculated, irrespective of the substrate used in the nursery. ((C) Inr a/Elsevier, Paris.).