Litsea cubeba (Lour.) Pers. is an important woody spice tree in southern China, and its fruit is a rich source of valuable essential oil. We surveyed and sampled L. cubeba germplasm resources from 36 provenances in nine Chinese provinces, and detected rich phenotypic diversity. The survey results showed that plants of SC-KJ, SC-HJ, and SC-LS provenance presented higher leaf area (LA); YN-SM and YN-XC plants had larger thousand-grain fresh weight (TFW); and HN-DX plants had the highest essential oil content (EOC). To explain the large differences in the phenotypes of L. cubeba among different habitats, we used Pearson’s correlation analysis, multiple stepwise regression path analysis, and redundancy analysis to evaluate the phenotypic diversity of L. cubeba. It was found that compared to other traits, leaf and fruit traits had more significant geographical distributions, and that leaf phenotypes were correlated to fruit phenotypes. The results showed that elevation, latitude, longitude, total soil porosity (SP), soil bulk density (SBD), and average annual rainfall (AAR, mm) contributed significantly to the phenotypic diversity of L. cubeba. Geographical factors explained a higher percentage of variation in phenotypic diversity than did soil factors and climate factors. Plants of SC-KJ and HN-DX provenances could be important resources for domestication and breeding to develop new high-yielding varieties of this woody aromatic plant. This study describes significant phenotypic differences in L. cubeba related to adaptation to different environments, and provides a theoretical basis for the development of a breeding strategy and for optimizing L. cubeba cultivation.

Litsea cubeba (Lour.) Pers. is an important economic tree. We aimed to explore the phenotypic diversity of wild L. cubeba provenances from Jiangxi province and identify the germplasms with desirable characteristics. Nest variance analysis, multiple comparisons, correlation analysis, path analysis, redundancy analysis, and cluster analysis were conducted to compare the phenotypes of 526 wild L. cubeba trees from 27 provenances. We detected significant differences in the growth traits, fruit traits, and essential oil (EO) content of L. cubeba provenances, as well as significant differences in tree height, thousand seed dry weight, and the proportion of five essential oil components (citral, neral, geranial, D-limonene, and citronellal) within the provenances. The fresh fruit yield (FFY) was mainly determined by the ground diameter and the annual average minimum temperature. The EO content was mainly affected by the water content, annual average temperature, longitude, and latitude. The proportion of citral (CitrP) was negatively affected by extreme low temperatures. Four individual L. cubeba trees had a high FFY of over 10.00 kg·tree⁻¹. Two trees had a high EO content exceeding 5%, with their CitrP over 80%. The provenances with high FFY were Guixi and Yushan (2.65 kg·tree⁻¹; 2.89 kg·tree⁻¹). The provenances with a high EO content of about 4.00% were Dayu, Yudu, Ji’an, Xinfeng, and Yushan. The provenance with the highest CitrP level (80.61%) was Ningdu.

To explore the radial variation in wood properties of slash pine (Pinus elliottii Engelm.) during its growth process and to achieve the early prediction of these properties, our study was carried out in three slash pine harvest-age plantations in Ganzhou, Jian, and Jingdezhen, Jiangxi province of South China. Wood core samples were collected from 360 sample trees from the three plantations. SilviScan technology was utilized to acquire wood property parameters, such as tangential fiber widths (TFWs), radial fiber widths (RFWs), fiber wall thickness (FWT), fiber coarseness (FC), microfibril angle (MFA), modulus of elasticity (MOE), wood density (WD) and ring width (RD). Subsequent systematic analysis focused on the phenotypic and radial variation patterns of wood properties, aiming to establish a clear boundary between juvenile and mature wood. Based on determining the boundary between juvenile and mature wood, a regression equation was used to establish the relationship between the properties of juvenile wood and the ring ages. This relationship was then extended to the mature wood section to predict the properties of mature wood. Our results indicated significant differences in wood properties across different locations. The coefficients of variation for RD and MOE were higher than other properties, suggesting a significant potential for selective breeding. Distinct radial variation patterns in wood properties from the pith to the bark were observed. The boundary between juvenile and mature wood was reached at the age of 22. The prediction models developed for each wood property showed high accuracy, with determination coefficients exceeding 0.87. Additionally, the relative and standard errors between the measured and predicted values were kept below 10.15%, indicating robust predictability. Mature wood exhibited greater strength compared to juvenile wood. The approach of using juvenile wood properties to predict those of mature wood is validated. This method provides a feasible avenue for the early prediction of wood properties in slash pine.

Litsea cubeba is an important industrial plant valued for its pericarp essential oil and kernel oil. However, variation in seed traits and kernel oil characteristics among wild populations and their relationships with ecological factors remain insufficiently understood. Wild germplam from 21 provenances across eight provinces in southern China was evaluated for seed traits, kernel oil content, and fatty acid composition, and variance analysis, correlation and path analysis, and multivariate ecological analyses were used to characterize phenotypic diversity and examine its associations with environmental variables. Analysis of variance showed that the investigated provenances differed significantly in seed traits and kernel oil characteristics (P < 0.05). Provenances ZJ-LY and SC-KJ exhibited relatively high kernel oil content (≥ 35%), whereas YN-XC, GZ-ZY, and SC-KJ showed higher seed yields (SY, ≥ 1000 g.tree^-1). In addition, kernel oil from Yunnan provenances was characterized by relatively high lauric acid content (C_12:0, ≥ 60%). Variance partitioning analysis revealed that provenance effects accounted for the majority of variation in seed and kernel oil characteristics. Seed and its kernel oil yield showed greater diversity than its oil content and components. Based on the RDA analyses, annual average relative humidity, annual average rainfall, soil pH, soil maximum water-holding capacity, soil total potassium, soil water content, and longitude were identified as the main environmental correlates of seed and kernel oil characteristics. Greater kernel oil accumulation was associated with higher annual minimum temperature, higher soil total potassium, and higher latitude, whereas less favorable fatty acid composition was associated with higher soil water content and longitude; in addition, greater C_12:0 accumulation was associated with higher annual maximum temperature and higher soil water content. These findings reveal substantial variation in seed traits and kernel oil characteristics among wild L. cubeba populations in southern China. Provenances ZJ-LY and SC-KJ are promising candidates for breeding programs targeting high kernel oil content. Moreover, the identified associations of kernel oil accumulation and fatty acid composition with annual minimum temperature, soil water status, and soil nutrients provide useful guidance for germplasm selection and cultivation management.

Objective The effects of spraying calcium chloride（CaCl₂），salicylic acid （SA）and 2，4-epibrassinolide （EBR）on the cold resistance of Choerospondias axillaris seedlings are investigated，and the treatment and concentration of enhancing the cold resistance of seedlings are screened out to provide a basis for enhancing the cold resistance of C. axillaris seedlings to low temperature in winter or late spring cold snaps. Method Using one-year-old potted seedlings of C. axillaris derived from seeds as the experimental materials，a randomized block experimental design was adopted.From November 10th to 20th，the seedlings of C. axillaris in three experimental plot groups were respectively subjected to foliar spraying of CaCl₂（C1，C2，C3），SA（S1，S2，S3）and EBR（B1，B2，B3）six times（once every two days），and then the seedling branches of each spraying treatment were treated with low temperature stress at 4 ℃ for 12 h.The anatomical structure of the leaves after stress treatment was observed by paraffin section method，and the changes of physiological indexes of the branches were measured. Result Compared with spraying water（CK），the cell density of palisade tissue in leaves of C. axillaris increased after spraying CaCl₂，SA and EBR.Among them，the upper epidermal thickness was the largest in the treatment of 10 mmol/L SA.The thickness of the lower epidermis treated with 1 mmol/L CaCl₂ was the largest，and the palisade tissue treated with 0.1 mg/L EBR was thicker.Under the treatment of 10 mmol/L CaCl₂，the thickness of sponge tissue，leaf thickness and leaf porosity increased，and the ratio of palisade tissue to spongy tissue and leaf tightness decreased.After spraying 20 mmol/L SA，the relative conductivity content in the stem of C. axillaris was significantly lower than that of CK，which was 12.07%.The content of malondialdehyde after 0.1 mg/L EBR treatment was lower than that of other treatments and CK，which was only 0.039 μmol/g.In addition to spraying 0.01 mg/L EBR and 0.1 mg/L EBR，the soluble sugar content in the stem of C. axillaris was slightly higher than that of the control，and the soluble sugar under other treatments was reduced to varying degrees compared with the control.Compared with CK，after spraying CaCl₂，SA and EBR，the contents of soluble protein and proline（except 1 mg/L EBR）and the activities of SOD and POD（except 10 mmol/L CaCl₂）in the stems of C. axillaris were increased by varying degrees.Through the principal component analysis of leaf anatomical structure index and physiological index，the treatment effect of three different exogenous substances from strong to weak was 10 mmol/L SA，1 mmol/L CaCl₂，20 mmol/L CaCl₂，1 mmol/L SA，10 mmol/L CaCl₂，20 mmol/L SA，0.1mg/L EBR，0.01 mg/L EBR，1 mg/L EBR，CK. Conclusion The treatment of three different exogenous substances is beneficial to enhance the cold resistance of C. axillaris seedlings.The effect of SA treatment is better than that of CaCl₂ and EBR，and the cold resistance of C. axillaris treated with 10 mmol/L SA is the best.