Response Surface Modeling and Comprehensive Growth Evaluation of Containerized Quercus myrsinifolia Blume. Seedlings under Varying NPK Ratios

초록

This study was conducted to determine the optimal N, P, and K fertilizer composition for the growth of containerized Quercus myrsinifolia Blume seedlings by analyzing trait-specific growth responses and selecting superior treatments using response surface methodology (RSM) and a comprehensive growth index (CGI). Fifteen fertilizer treatment combinations and an untreated control were established by varying the ratios of nitrogen, phosphorus, and potassium within the ranges of N (urea) 1.5, 1.75, and 2.00 g L-1; P (fused phosphate fertilizer) 0.9, 1.4, and 1.9 g L-1; and K (potassium phosphate) 1.5, 1.75, and 2.00 g L-1. For three months after fertilizer application, height, root collar diameter (RCD), H/D ratio, leaf length, leaf width, and number of leaves were measured. The quadratic response surface regression showed that the model fit differed among growth traits, with relatively high coefficients of determination for leaf length, height, and H/D ratio. Height and H/D ratio were significantly affected by the P × K interaction, whereas leaf length was influenced by N, K, N × K, and K terms, indicating that seedling growth responses were determined by nutrient balance and interaction effects rather than by a single nutrient alone. In the CGI analysis, T4 containing N, P, and K at concentrations of 2.0, 1.4, and 1.5 g L-1, ranked highest in both Equal CGI and Weighted CGI, with values of 0.741 and 0.772, respectively. T5 (1.75:1.4:1.75) ranked second in both indices, while T2 and T6 showed different rankings depending on whether height and RCD were weighted more heavily or all traits were equally considered. These results indicate that the optimal NPK composition may vary depending on the target growth trait; however, T4 was identified as the most favorable candidate for promoting comprehensive growth of containerized Q. myrsinifolia seedlings. This study provides quantitative baseline information for establishing fertilization regimes and improving container seedling production techniques for warm-temperate evergreen broad-leaved tree species.

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