The properties of teak wood, such as natural durability and beautiful color, are closely associated with wood extractives. In order to further understand the performance differences between teak heartwood and sapwood, we analyzed the chemical components of extractives from 12 wood samples using an ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS)-based metabolomics approach. In total, 691 metabolites were identified, and these were classified into 17 different categories. Clustering analysis and principal component analysis of metabolites showed that heartwood samples could be clearly separated from sapwood samples. Differential metabolite analysis revealed that the levels of primary metabolites, including carbohydrates, amino acids, lipids, and nucleotides, were significantly lower in the heartwood than in the sapwood. Conversely, many secondary metabolites, including flavonoids, phenylpropanoids, and quinones, had higher levels in the heartwood than in the sapwood. In addition, we detected 16 specifically expressed secondary metabolites in the heartwood, the presence of which may correlate with the durability and color of teak heartwood. Our study improves the understanding of differential metabolites between sapwood and heartwood of teak, and provides a reference for the study of heartwood formation.

Appropriate fertilization can enhance forest productivity by maintaining soil fertility and improving the structure of the bacterial community. However, there is still uncertainty surrounding the effects of combined application of organic and inorganic fertilizers on soil nutrient status and bacterial community structure. A fertilization experiment was set up in an eight-year-old teak plantation with five treatments involved: mixed organic and NPK compound fertilizers (OCF), mixed organic and phosphorus fertilizers (OPF), mixed organic, NPK and phosphorus fertilizers (OCPF), mixed NPK and phosphorus fertilizers (CPF) and no fertilization (CK). Soil chemical properties and bacterial communities were investigated, and the co-occurrence pattern of the bacterial community under different fertilization treatments was compared. The results showed that the contents of soil organic matter and nitrate nitrogen, and the soil pH values were the highest after OCPF treatment, which were 20.39%, 90.91% and 8.16% higher than CK, respectively. The richness and diversity of bacteria underwent no obvious changes, but the structure of the soil’s bacterial community was significantly altered by fertilization. Of the dominant bacteria taxa, the relative abundance increased for Gemmatimonadetes, Myxococcota, ADurb.Bin063-13 and Candidatus_Koribacter, and decreased for Chloroflexi, Proteobacteria, JG30-KF-AS9 and Acidothermus under OCPF treatment in comparison to CK. The number of nodes and edges, the average degree and the network density of bacterial community co-occurrence networks were the greatest in OCPF treatment, indicating that application of OCPF could make the network structure of soil bacteria more stable and complex. Moreover, soil pH and organic matter were significantly correlated with bacterial community structure and were considered the main influencing factors. These findings highlight that the combined application of organic, NPK and phosphorus fertilizers is highly beneficial for improving soil quality and optimizing bacterial community structure in teak plantations.

In order to interpret the patterns of genetic variation of photosynthesis and the relationships with growth traits within gene resources of teak (Tectona grandis Linn.), gas exchange, and chlorophyll fluorescence parameters, growth traits of plants in nursery and field trials were measured for 20 teak clones originated from different countries. The results show that there was abundant genetic variation in gas exchange, chlorophyll fluorescence, and growth among the teak clones. The measured traits were found to have generally high heritability (h²) except for intercellular concentration of carbon dioxide (CO₂) (C_i). The net photosynthetic rate (P_n), seedling height, and individual volume of wood were significantly correlated with each other, and seedling height was significantly correlated with plant height in field trials, suggesting that P_n and seedling height can be useful in teak breeding. Teak clones 7029, 71-5, 7219, 7412, and 7122, and provenances 3070, 3074, and 3071 had higher photosynthetic rates, and can be regarded as a key resource in teak improvement programs. This work provides useful information for teak breeding and germplasm resource management.

As wild Aquilaria sinensis resources are exhausted and protected, China has established a huge number of plantations of Aquilaria trees and developed artificial induction techniques. However, the current output and quality of artificial induction technology have not yet met the expected results. It has been found that high-oil-containing agarwood may contain particular fungal stains associated with agarwood production. To enhance the quality of agarwood, we recovered and characterized three highly active fungi from high-oil-containing agarwood and inoculated them onto A. sinensis trees using two traditional physical methods. The results showed that fungi extracted from high-oil-containing agarwood can effectively increase the yield and quality of agarwood. During the agarwood formation process, parenchyma cells, xylem rays, and axial parenchyma cells in the xylem gradually undergo apoptosis, thereby promoting the expansion of the color range of agarwood. Nine months after the treatment, the alcohol-soluble extract content in agarwood reached the standard specified in the Chinese Pharmacopoeia (10%), and the proportions of sesquiterpenes and chromones in each treatment were 55.82%, 58.31%, 62.65%, 70.97%, and 13.71%, respectively. These results indicate that fungal induction has a positive impact on the quality of agarwood. In addition, compared to drilling and fungus combined induction, “burning holes and fungi” combined induction demonstrates better results and can further improve the yield and quality of agarwood.