Differential and Interactive Effects of <i>Scleroderma</i> sp. and Inorganic Phosphate on Nutrient Uptake and Seedling Quality of <i>Castanea henryi</i>

Both ectomycorrhizal fungi (ECMF) and inorganic phosphate (Pi) can improve plant growth. However, the relationship between Pi levels and mycorrhizal colonization rate is divergent, and information on the differential and interactive effects of Pi levels and ECMF on nutrient uptake and seedling quality is lacking. We conducted a study on 4-week-old <i>Castanea henryi</i> ‘You Zhen’ seedlings by inoculating with <i>Scleroderma</i> sp. (+ECM) to compare with uninoculated (-ECM), under low Pi level (-Pi) and high Pi level (+Pi). The mycorrhizal colonization rate, seedlings morphological and physiological parameters, nutrient uptake content, and the rhizosphere soil enzymatic activities and chemical properties were investigated. Results indicated that the mycorrhizal colonization rate at low Pi level (84 ± 2%) was higher than that at high Pi level (71 ± 2.52%). No matter the Pi level, inoculating with ECMF significantly improved seedling dry weight, height, diameter, and seedling quality index (SQI). The +ECM+Pi and +ECM-Pi treatments significantly increased SQI by 282.76% and 232.76% in comparison to the -ECM-Pi treatment, respectively. Applied Pi had no significant effect on SQI. ECMF inoculation significantly increased nitrogen (N), phosphorus (P), and potassium (K) uptake in roots, stems, and leaves, while Pi application increased the P uptake in roots only. There was no significant interaction between ECMF and Pi levels on seedling quality and nutrient uptake (except P uptake in leaf). Results indicated that ECMF is a suitable alternative to the use of phosphorus fertilizer in nursery production of <i>C. henryi</i> seedlings in terms of protecting the environment, saving resources, and reducing production costs.