The effects of single species, dual species and indigenous mycorrhiza inoculation on citrus growth and nutrient uptake

The objective of this study was to evaluate the effects of selected single arbuscular mycorrhiza (AM) species, dual species inoculations and indigenous mycorrhizae (IM) inoculations, using specific growing media (GM), on the growth and nutrient uptake of sour orange (Citrus aurantium L.) seedlings. Five mycorrhiza species and their dual species inoculations, one commercial and one indigenous (multiple species) mycorrhizae were investigated using two growing media, GM1 (andesitic tuff + peat (1:1, V:V)) and GM2 (andesitic tuff + peat + soil (4 + 5+1, V: V:V)), under controlled greenhouse conditions. The experiments were conducted over 12 months. Mycorrhizal inoculation increased certain plant growth parameters such as shoot height, diameter, and shoot and root dry matter. Generally, mycorrhiza species and their dual species inoculations exerted different responses on plant growth. In GM1, Funneliformis mosseae, Rhizophagus clarus and indigenous mycorrhiza (IM) species were the best inoculants to increase citrus growth, root colonization and nutrient uptake; however, in GM2, Fu. mosseae and IM were the best inocula. Fu. mosseae + R. clarus was the most efficient dual species inoculation in GM1, whereas in GM2 the most efficient combination was Fu. mosseae + Fu. caledonium. The beneficial effects of AM fungi and the dual species inoculation with IM was also significant. Citrus seedlings grew much better in GM1 than in GM2. Root colonization was also increased with dual species inoculation and IM. In addition, the plant phosphorus and zinc content increased with mycorrhizal inoculation. Our results reinforce the efficiency of IM and mycorrhizal inoculations as being as effective as exotic AM fungal isolates. Dual species inoculation and IM show promise in the production of healthy seedlings, using several growing media.