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 m ycorrhizal fungi (AMF) and bacteria on the growth of micropropagated potato (Solanum tuberosum) transplanted to a peat-based substrate were found in t hree 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 Gl omus fistulosum plus bacteria B1 in greenhouse beds or with a mixture of Gl omus manihotis and two bacteria in shadowhouse beds resulted in higher numb er of minitubers (NT), higher weight per minituber or in higher total weigh t of minitubers per plant. However, the effects of mycorrhization varied fo r two different potato varieties and the synergistic effects of coinoculati on with different bacteria isolated from rhizosphere or hyphosphere was not significant in most cases. There were no significant effects of Zeolite (c linoptinolite clay) amendment on the mycorrhization and aboveground growth of potato plants, while slight stimulation was observed for minituber weigh t. The inoculation into peat-based substrate might be successful regarding plant growth response; however, to increase the potential of the inoculatio n 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. (C) 2000 Elsevier Science B.V. All rights reserved.