Infectivity and effectieness of different species of arbuscular mycorrhizal fungi in micropropagated plants of Mr S 2/5 plum rootstock

Micropropagated plum plants (Prunus cerasifera Ehrh clone MrS 2 5) were inoculated with 4 different species of arbuscular mycorrhizal fungi (Glomus mosseas, G caledonium, G coronatum and Glomus strain A6) after transfer from an in vitro to an in vivo system. The most and the least infective fungi, G mosseae and G coronatum respectively, were tested for their growth-promoting abilities with respect to the micropropagated plum plants. Both fungi improved plant growth in comparison with uninoculated plants. G coronatum showed a prolonged lag phase during the early stage of mycorrhizal infection and affected growth less than G mosseae at the first harvest (4 wk). At the second harvest (14 wk), when mycorrhizal infection by both fungi was high, G coronatum was as effective as G mosseae in promoting plant growth of P cerasifera. The importance of a rapid mycorrhizal infection during the acclimatization phase of micropropagated plants is discussed in this paper.