Oil tea camellia (Camellia spp.) is an important woody oil crop with a high nutritional and economic value. Whole-genome resequencing (WGR) technology can provide an in-depth understanding of the genetic background of this plant as well as a reference for breeding research, germplasm resource conservation, and genetic modification. In this study, we analyzed SNP and InDel variations in 49 individual oil tea camellia germplasm samples collected from five populations located in three provinces of China: Hainan, Guangdong and Guangxi. The samples were analyzed through WGR after the ploidy of the samples was determined through flow cytometry. A total of 239,441,603 high-quality single nucleotide polymorphisms (SNPs) and 23,510,374 high-quality insertion/deletion variation sites (InDels) were obtained. The distribution of SNPs and InDels in different functional regions differed significantly, with a high density of variations in non-coding regions, such as intergenic regions and introns, and a relatively low density of variations in coding regions. Transition was the main type of SNP variation. A population genetic diversity analysis revealed that the sampled oil tea camellia populations exhibited a high genetic diversity and extensive genetic variation. The genetic diversity of the oil tea camellia populations in the Hainan region was higher than inland regions. This study also determined the genetic diversity of and variations between octoploid and decaploid oil tea camellia in the tropics and between Hainan-based and inland oil tea camellia. Such findings provide a reference for the conservation of germplasm resources and the genetic modification of oil tea camellia.

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.