Effects of compound fertilizer and microbial inoculum on growth， photosynthesis， and nutrient accumulation of Alpinia hainanensis seedlings

【Objective】 This study aimed to explore the effects of different fertilization treatments on the growth， photosynthesis characteristics and nutrient uptake and utilization of Alpinia hainanensis seedlings，so as to provide a reference for fertilization of the plant at seedling stage.【Method】 Three-month-old Alpinia hainanensis seedlings （initial plant height of 8.9 cm and plant number of 1） were used as test materials in the a pot experiment. Five compound fertilizer and microbial inoculum treatments were set： 2.5 g/plant compound fertilizer（C1），5.0 g/plant compound fertilizer（C2），5.0 g/plant microbial inoculum（S），2.5 g/plant microbial inoculum+2.5 g/plant compound fertilizer（M1），and 1.0 g/plant microbial inoculum+4.0 g/plant compound fertilizer（M2） treatments. Non-fertilization treatment was taken as the control（CK）. The growth indexes，photosynthesis indexes， and nutrient contents were determined to conduct correlation analysis and fuzzy membership function analysis on each index.【Result】 Under the treatment of different compound fertilizers and microbial inocula，most indexes of Alpinia hainanensis seedlings were better than those of CK，and most treatment groups showed significant differences （P<0.05）or extremely significant differences（P<0.01）. Effects of applying compound fertilizer alone （C2） were better than that of applying microbial agent inoculum （S），and effects of appropriate combined application of microbial inoculum and compound fertilizer were better than that of applying any of them alone. In the treatment of single application （C1 and C2） and combined application （M1 and M2） of fertilizers， with the increase of compound fertilizer application dosage，the above-ground part growth indexes，dry matter accumulation，photosynthesis indexes， and nutrient contents were all improved to varying degrees. Correlation analysis results showed that： the growth indexes， dry matter accumulation， and nutrient content of Alpinia hainanensis seedlings under compound fertilizer and microbial inoculum treatments were closely correlated； the nutrient content in root and leaf had a strong correlation with other indexes， while the total carbon （TC）， total nitrogen （TN）， and total potassium （TK） contents in stem had a relatively strong correlation with other indexes， which was lower than that of root and leaf. The ranking of the average membership degrees of each treatment from largest to smallest was M2>C2>M1>C1>S>CK.【Conclusion】 Appropriate combined application of microbial inoculum and compound fertilizer effectively promotes the growth and dry matter accumulation of Alpinia hainanensis seedlings， enhances their photosynthetic ability， and facilitate nutrient accumulation. The treatment of 1.0 g/plant of microbial inoculum+4.0 g/plant of compound fertilizer shows the best effects. During the cultivation of Alpinia hainanensis seedlings，attention should be paid to its nitrogen supply and utilization，and proper probiotic inocula should be applied to promote the growth and development of Alpinia hainanensis seedlings.