To determine optimal light conditions for Hopea hainanensis Merr. & Chun seedling growth, this study examined growth and physiological parameters under four shading treatments (0%, 30%, 60%, and 90% irradiance reduction) over 12 months. Shading significantly affected the growth adaptability of seedlings. As shading increased, height, leaf traits (area, length, width), and light saturation point all initially increased, peaked at 30% shading, and then decreased. Conversely, basal diameter, leaf thickness, the maximum net photosynthetic rate, net photosynthetic rate, photosynthetic quantum efficiency, transpiration rate, and stomatal conductance progressively declined as shading increased. Biomass accumulation (in stems and roots), dark respiration rate, and light compensation point exhibited a U-shaped response to shading, being minimized under low or moderate shading. All shading treatments significantly reduced biomass and photosynthetic performance compared to controls. Multivariate analysis identified 0%–30% shading as optimal for cultivation, with 30% shading enhancing photomorphogenic responses while maintaining photosynthetic efficiency. The study findings suggest a novel seedling cultivation protocol for nursery use, in which initial establishment occurs under 30% shading to maximize vertical elongation, followed by the progressive reduction in shading to stimulate radial growth and optimal biomass partitioning. This approach mimics natural canopy gap dynamics, effectively mimicking natural regeneration in tropical rainforest ecosystems.

Valued for furniture, crafts, and medicine, Dalbergia odorifera T. C. Chen confronts critically depleted wild populations and slow cultivation growth, necessitating precision nutrient formulation to overcome physiological constraints. Using a ‘3414’ regression design with four levels of N, P, and K, this study identified phosphorus (P) as the most influential nutrient in regulating growth (P > N > K). Maximal growth enhancement occurred under T7 (N2P3K2), with height and basal diameter increments increasing by 239% and 128% versus controls (p < 0.05). Both traits exhibited progressive gains with rising P but unimodal responses to N and K, initially increasing then declining. T7 boosted total biomass by 50% (p < 0.05) with stem-biased partitioning (stem > root > leaf; 52%, 26%, 22%). Photosynthetic capacity increased significantly under T7 (p < 0.05), driven by P-mediated chlorophyll gains (Chla + 70%; Chlb + 75%) and an 82% higher net photosynthetic rate. Metabolic shifts revealed peak soluble sugar in T7 (+139%) and soluble protein in T9 (+226%) (p < 0.05), associated primarily with P and K availability, respectively. Correlation networks revealed significant associations among structural growth, photosynthesis, and metabolism. Principal component analysis established T7 as optimal, defining a “medium-N, high-P medium-K” precision fertilization protocol. These findings elucidate a phosphorus-centered regulatory mechanism governing growth in D. odorifera, providing a scientific foundation for efficient cultivation.

Dalbergia odorifera T. Chen is a rare and endangered tree species endemic to China. However, efficient cultivation protocols for high-quality seedling production remain to be optimized. This study investigated the interactive effects of shading intensity and container type on seedling growth, photosynthesis, antioxidant systems, and resource allocation. A two-factor completely randomized design was used with five shading levels (0%, 20%, 40%, 60%, and 80%) and three container types (rigid plastic pots, non-woven fabric containers, and black plastic bags). Shading suppressed growth by limiting carbon assimilation, with total dry weight reduced by 93–94% under heavy shade, triggering a carbon–antioxidant trade-off. Moderate shading (40–60%) increased antioxidant enzyme activities, but 80% shading caused antioxidant dysfunction and membrane lipid peroxidation, with malondialdehyde (MDA) content increasing by 343%. Non-woven fabric containers improved root development and maintained higher photosynthetic efficiency under shade, whereas black plastic bags exacerbated stress. Container type significantly interacted with shading intensity: non-woven fabric containers performed best under 0–20% shading, while rigid plastic pots showed advantages under 60–80% shading. Principal component analysis identified full sunlight combined with non-woven fabric containers as the optimal cultivation model. These findings suggest that container type modulates light responses, potentially through changes in the rhizosphere environment, and offer practical guidance for precision cultivation of D. odorifera and other valuable tree species.