Arbuscular mycorrhizal and soil fertilization on post-transplant development of outplants of seven forest species

Abstract

Seedling of seven forest species were raised in conventional nursery substrate either infested or not with a mixture of arbuscular mycorrhizal fungi (Glomus etunicatum, Gigaspora margarita and Acaulospora scrobiculata) and transplanted into plastic pots with a low-fertility Oxisol amended with low or high NPK-fertilization and with or without re-inoculation. It was found that either inoculation at nursery or at transplanting stage guaranteed high root colonization (>70%), growth response and favorable nutrition after transplant. Growth effects varied with treatments and with plant species. Inoculation benefits for shoot dry matter were as high as 800% for Colvillea racemosa. Reduced growth was observed when seedling non-inoculated at nursery stage were also not inoculated at transplanting, whereas nursery-inoculated ones grew well independently on soil fertility and re-inoculation. Enhanced soil fertility did not increase shoot dry matter yield of Luehea grandiflora, Senna macranthera and Enterolobium contortisiliquum. It increased dry matter of Cecropia pachystachya in the absence of mycorrhiza; of mycorrhizal Senna multijuga and C. racemosa and of Sesbania virgata caused an increase in all treatments. Only C. racemosa did not respond to inoculation at transplanting.