Response of micropropagated potatoes transplanted to peat media to post-vitro inoculation with arbuscular mycorrhizal fungi and soil bacteria

Positive effects of dual inoculation with some combinations of arbuscular mycorrhizal fungi (AMF) and bacteria on the growth of micropropagated potato (Solanum tuberosum) transplanted to a peat-based substrate were found in three different cultivation systems — pots, greenhouse or shadowhouse beds. Some inoculation treatments, e.g. with Glomus etunicatum, Glomus fistulosum together with bacterial isolate B1 (Bacillus subtilis) in pots, or with Glomus fistulosum plus bacteria B1 in greenhouse beds or with a mixture of Glomus manihotis and two bacteria in shadowhouse beds resulted in higher number of minitubers (NT), higher weight per minituber or in higher total weight of minitubers per plant. However, the effects of mycorrhization varied for two different potato varieties and the synergistic effects of coinoculation with different bacteria isolated from rhizosphere or hyphosphere was not significant in most cases. There were no significant effects of Zeolite (clinoptinolite clay) amendment on the mycorrhization and aboveground growth of potato plants, while slight stimulation was observed for minituber weight. The inoculation into peat-based substrate might be successful regarding plant growth response; however, to increase the potential of the inoculation in practical production of potato minitubers, it is necessary to consider possible differences of various potato varieties and to select appropriate combination of bacteria and AMF symbionts. © 2000 Elsevier Science B.V. All rights reserved.