Under sterilized and non-sterilized soil conditions, mycorrhizal dependency in citrus plants depends on phosphorus fertilization rather than zinc application

The soils of the cukurova Region (Eastern Mediterranean coast of Turkey) have high clay, Oland lime content; consequently, crop production is limited as zinc (Zn) and phosphorus (P) deficiency are common problems in citrus plantations. The objective of this study was to evaluate the effects of a single selected arbuscular mycorrhiza (AM) and indigenous mycorrhizae (IM) inoculations, using sterile and non-sterile soils, and the application of P and Zn doses on the growth and nutrient uptake of sour orange (Citrus aurantium L.) seedlings. Experiments were performed under greenhouse conditions using a Canakci soil series (Typic xerofluvent) over 8 months. Rhizoglomus clarum was used as the arbuscular mycorrhizae fungus at a level of 1000 spores per plant. Different P (0 and 200 mg kg(-1) P2O5) and Zn (0, 2.5, 5 mg kg(-1) Zn) rates were applied at the beginning of the experiment. Generally, plants grown in non-sterile soils grew better than those in sterile soils. Mycorrhizal inoculation increased certain growth parameters, such as shoot height, shoot diameter, shoot and root dry matter, and root colonization in not only sterile but also non-sterile soils. However, mycorrhizal inoculation in sterile soil significantly increased plant biomass and nutrient uptake. The results show that the non-sterile soil significantly increased citrus dry matter production, % root colonization, and P and Zn uptake compared to sterile soil. In non-inoculated, sterile soils, plant P and Zn content was significantly reduced compared with inoculated plants. In addition, in sterile soil, the seedling P and Zn concentration increased upon mycorrhizal inoculation. Inoculation dependency was significantly affected by soil sterilization and partly by P application but not by Zn application. Under non-sterile soil conditions, since there was native mycorrhiza spores mycorrhizal dependency (MD) was very low and also increasing P addition have reduced mycorrhizal dependency.