Mycorrhizal inoculation and phosphate fertilizer in the production of seedlings of the forage peanut

ABSTRACT To evaluate the effect of mycorrhiza and phosphorus (P) on the forage peanut (Arachis pintoi Krap. & Greg.), two experiments were set up in a greenhouse to prove the hypothesis that mycorrhiza is beneficial to the growth of seedlings of the species, for both seed and vegetative propagation. In the first experiment, the seedlings were grown in trays of 72 cells filled with soil, in a completely randomised design (CRD), with split lots. The treatments consisted of the inoculation of six species of arbuscular mycorrhizal fungi (AMF) for the lots, and two methods of propagation for the sub-lots. In the second experiment, stolons were grown in pots, in soil of low fertility treated with five doses of P and inoculated with four species of AMF, and one control, arranged in a 5 x 5 factorial in CRD. In both experiments, the substrates had earlier been sterilised. Seedlings originating from seeds, and grown in Styrofoam trays, produced more dry matter than those obtained vegetatively, with the AMF being effective in promoting seedling growth. For those seedlings originating from stolon rooting, the benefit from the mycorrhiza was detected only for root mass. In the seedlings grown in pots and fertilised with P, the extent of the response was higher for those inoculated with AMF. The species G. clarum was more efficient under conditions of low P availability, while A. morrowiae excelled at higher levels of P. There are indications of high mycorrhizal dependency in the forage peanut.