Seasonal Variation in Root Morphological Traits and Non-Structural Carbohydrates of Pinus yunnanensis Seedlings Across Different Seedling Orders.

Non-structural carbohydrates (NSCs), comprising soluble sugars (SS) and starch (ST), are essential for plant growth and development. The distribution of SS and ST concentration across various organs fluctuates throughout time due to the changes in root morphology in plants, ultimately demonstrating multiple strategies for adapting to seasonal environmental variations. The purpose of this investigation was to explore the seasonal dynamic patterns of root morphology in Pinus yunnanensis, with particular emphasis on specific root length (SRL), specific root surface area (SRA), root tissue density (RTD), and average diameter (AD). This study also aimed to investigate the seasonal fluctuation patterns of NSC. The SRL, SRA, RTD, and AD in both first-order and second-order seedlings had analogous fluctuation patterns from March to December. Although the SRL, SRA, RTD, and AD of third-order seedlings exhibited minor differences from the preceding orders, the overall variance patterns corresponded with those of the first two seedling groups. Consequently, the seasonal fluctuations in SS, ST, and NSC levels in various seedling orders exhibited patterns similar to root morphological characteristics. The SRL, SRA, and AD of three seedling orders exhibited a significant correlation with SS, ST, and NSC, confirming the link between NSC concentration and root morphology. The responses of SS, ST, and NSC in various organs of P. yunnanensis seedlings to root morphological characteristics further substantiated the correlation between the variations in NSC across different organs and root morphological traits.