Effect of arbuscular mycorrhizal fungi and phosphorus fertilization on the post vitro growth and yield of micropropagated strawberry grown in a sandy loam soil

Strawberries (Fragaria ×ananassa Duch.) grown in alfisols of semiarid areas in India results in suboptimal yields. Low organic carbon and low phosphorus (P) availability, in addition to high P fixation, affects P availability drastically, even when it is applied externally. The benefit to the yield of micropropagated strawberry Fragaria ×ana nassa 'Pajaro' through inoculation with arbuscular mycorrhizal (AM) fungi and P application was examined in a field experiment. AM response was evaluated at four doses of P (50, 100, 150, and 200 kg P·ha–1) in a high P-fixing capacity and P-deficient alfisol. At harvest, all inoculated plants, except those at the highest level of applied P (200 kg·ha–1), had larger fruit yields per plant, unit mass, number of runners, higher shoot dry matter, and shoot P content. However, the AM response as measured by yield varied with P concentration. Inoculated plants had a significantly greater fruit yield when grown at 150 kg P·ha–1, and the yield was comparable with uninoculated plants grown at 200 kg P·ha–1. The external P requirements were 71 kg·ha–1 for mycorrhizal and 106 kg·ha–1 for nonmycorrhizal strawberry plants to obtain 90% of the maximum fruit yield. In terms of P fertilization, this corresponds to a savings of 35 kg·ha–1. The percent mycorrhizal root length colonization, both in inoculated and noninoculated plants, was not found to differ significantly with P application.Key words: strawberry, P fertilization, mycorrhizal dependency.