Arbuscular Mycorrhizal Fungi and Acclimatization of Micropropagated Citrus

Micropropagated plantlets lack mycorrhizal symbionts and therefore present some physiological hindrances when transferred from axenic to ex vitro conditions. The purpose of the present study was to research the effects of Glomus mosseae and G. versiforme on growth, photosynthesis, and nutrient uptake of micropropagated citrus plantlets at the acclimatization stage. The two mycorrhizal fungi successfully colonized the roots of citrus plantlets after an acclimatization period of 170 days, and the mycorrhizal developments were apt to low levels. Inoculation with G. mosseae improved acclimatized growth performance; increased photosynthetic rates, transpiration rates, and stomatal conductance; and stimulated the accumulations of nitrogen (N), phosphorus (P), calcium (Ca), copper (Cu), zinc (Zn), and manganese (Mn) in leaves and roots compared to the noninoculated treatment. These observations suggested that only G. mosseae was the more efficient fungus, exhibited better adaptation to transplanted conditions, and therefore is appropriate to introduce into the micropropagation protocol of citrus.