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 substrates: sandy soil, peat and a commercial peat-bark compost mix, immediately after the weaning stage. After 3 months of growth under greenhouse conditions, plants were transplanted in a microplot set-up. At transplanting, differences in growth and in mycorrhizal colonisation were significantly related to the starter substrate used; plants grown in peat were taller than plants grown in soil or in the compost-peat mix. Although both soil-less growing media were less conducive than soil to AM colonisation, the compost-pear mix resulted in higher colonisation percentages. At the end of the first growing 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, and all plants presenting the symbiosis were bigger than those that had not been inoculated, irrespective of the substrate used in the nursery. ((C) Inra/Elsevier, Paris.).