【Objective】 Dalbergia odorifera T. Chen, commonly known as Hainan Huanghuali, Jiangxiang or Hualimu, belongs to the genus Dalbergia, family Papilionoideae. It is a unique redwood tree species in China and is used to make high quality furniture. The variation of provenance and provenance division of growth and wood basic density of D. odorifera were studied, and fast-growing, high-quality provenance was selected preliminarily, which provided strong seedlings for afforestation in Guangdong.【Method】 We analyzed growth (height, diameter at breast height (DBH) as well as single tree volume) and wood traits (wood base density and heartwood ratio) in the 11-year provenance test conducted in Yangjiang, Guangdong Province. Furthermore, we explored the correlation between phenotypic and genotypic characters and original geo-climatic factors. Based on the results generated from cluster analysis and membership function method, the provenances with superior growth and wood properties were selected at early stage. 【Result】 Significant or extremely significant provenance variations were observed in height, DBH, volume, wood basic density and heartwood ratio of D. odorifera, suggesting genetic differentiation among provenances. The variation ranges of provenance for DBH and tree volume were 3.07-13.73 cm and 0.002 156-0.050 541 m3, respectively. The maximum value of provenance was 4.47 and 23.44 times of the minimum value, and the coefficients of variation of provenance phenotype for DBH and tree volume were 26.01% and 61.99%, respectively. Compared to the growth character, the provenance differentiation of wood basic density was relatively small, with the values ranging from 0.416-0.768 g/cm3. The maximum value of provenance was 1.84 times of the minimum value, and the phenotypic variation coefficient of provenance was 8.85%. On an average, 33.54% of D. odorifera plants formed heartwood when 10 years old, and the variation range of provenance was 16.67%-50.00%. No significant positive correlation was observed between wood basic density and height, DBH and volume (0.60, 0.54 and 0.50, respectively). The DBH and volume of D. odorifera provenance were positively correlated with the ratio of heartwood. Correlation analysis and cluster analysis showed that the 8 provenances could be classified into 2 groups with clear geographic structure. The first group consisted of the Northeast coastal provenances zoo of Hainan Island, including Haikou, Wenchang and Wanning provenances, and the second group consisted of Midwest mountain provenances zoo of Hainan, including Bawangling, Dongfang, Wuzhishan, Baisha and Jianfeng provenances. Three growth characters and two wood characters ofD. odorifera were selected for comprehensive evaluation by membership function method used in fuzzy mathematics. The comprehensive evaluation of 8 provenances was different, ranging from 0 to 0.90. The highest average subordinate value was Baisha provenance (0.90), followed by Bawangling provenance (0.61). According to the final evaluation of the comprehensive score, the Baisha provenance was the best. The tree height, DBH, volume, basic density, and the proportion of forming heartwood of Baisha provenance were increased 5.61%, 14.04%, 42.78%, 0.33% and 17.23%, respectively.【Conclusion】 The genetic provenance differentiation of D. odorifera was related to location annual rainfall and average temperature. The local annual precipitation and average temperature were the main climatic factors which led to the variation of wood density for D. odorifera. The provenances tested from lower annual precipitation and annual average temperature region were not only higher in height,diameter and tree volume but also exhibited higher wood basic density and heartwood ratio. Baisha provenance from the middle mountain area with fast growing, highly-quality wood and higher heartwood forming ratio was considered to possess high adaptability for afforestation in Guangdong Province.
【Objective】 In this study, we documented the growth as well as photosynthetic and physiological characteristics of Dalbergia odorifera after injecting various concentrations of ethephon (ETH) with the aim of collecting data to provide a theoretical basis for efficient cultivation and later heartwood formation. 【Method】 Dalbergia odorifera with a DBH of 6-8 cm was taken as the research object and divided into 4 treatments groups, E0.1%, E0.5%, E2.5% and control group (CK). The effect of different treatments on the growth indicators ofD. odorifera, namely, growth indicator increment, SPAD value, specific leaf area (SLA), water use efficiency (WUE) and photosynthetic parameters was studied. 【Result】 Among the 3 ethephon treatments, the DBH increase (ΔD) with E0.1% and E0.5% treatments was larger than that of CK by 8.97% and 6.07%, respectively. Both the increase in tree height (ΔH) and the volume of the individual tree (ΔV) with E2.5% treatment were lower compared to CK with a decrease of 67.39% and 59.33%, respectively. Ethephon had a significant effect on the SPAD value of D. odorifera, and the order was E0.1%> E0.5%> CK> E2.5%. The leaf dry weight and leaf area were significantly higher at E0.1% and E0.5% compared to E2.5%. The order of SLA was E0.1%>E0.5%>CK>E2.5%. According to the Pearson correlation analysis, all ETH treatments had a significant negative effect on both SLA and WUE. The photosynthetic parameters obtained from the light response curve showed that the maximum net photosynthetic rate (Pn, max), initially increased, and then decreased with increasing concentration of ETH. The rate for E0.1% and E0.5% was higher than that for CK by 38.00% and 26.22%, respectively. The light saturation point (PLsp), initially increased, and then slightly decreased with increasing concentration of ETH injected. The values for all the treatments were higher than that for CK while those it was the highest for E0.5%. The light compensation points (PLcp) for all ETH-treated groups were lower than that for CK, and those for E0.1% and E0.5% were significantly lower than that for CK by 16.37% and 20.92%. 【Conclusion】 Low concentration of ETH could facilitate the chlorophyll content ofD. odorifera, SLA, Pn and other photosynthetic characteristics; at a high concentration of 2.5%, ETH was counterproductive to the height and individual tree volume increase of D. odorifera.
【Objective】 Dalbergia tonkinensis Prain, commonly known as Mai Dou Lai in Vietnam is a semi deciduous tree belonging to the genus Dalbergia, family Papilionoideae. The genetic variability and genetic-phenotypic correlations among growth traits were studied for screening the excellent genetic materials of D. tonkinensis at an juvenile stage. It helped the germplasm introduction of D. tonkinensis and the development of precious timber industry in Guangdong Province. 【Method】 The growth traits include tree height, diameter at breast height, diameter at ground height, crown, leaf chlorophyll SAPD value and leaf area were studied in the 4 years old, provenance/family testing trail in Baishengyuan, Yangjiang City, in west Guangdong Province. The genetic parameters were estimated for each trait using mixed linear model. Further, we selected the excellent provenances and families using exponential equation.【Result】 The average annual growth in height and ground diameter of D. tonkinensis was 1 m and 3 cm, respectively. The coefficient of variation of diameter (26.86%-40.41%) was higher than that of tree height (25.27%-26.35%). There were different phenotypic and genetic variations in the growth characters for D. tonkinensis. The phenotypic variation coefficient ranged from 10.81% (leaf chlorophyll SPAD value) to 36.97% (ground diameter 17). The genetic variation coefficient ranged from 4.20% (leaf chlorophyll SPAD value) to 10.95% (ground diameter 17). The coefficient of variation of tree height was consistent among all the characteristics at juvenile stage. The provenance repeatability, family and individual heritability were recorded as (0.45±0.19) to (0.81±0.06), (0.27±0.16) to (0.59±0.09) and (0.18±0.13) to (0.35±0.19), respectively. Highly significant positive genetic correlation was observed between growth characters (P < 0.01). Significant ( P < 0.05) or extremely significant genetic positive correlation ( P < 0.01) was observed between growth traits and leaf chlorophyll SPAD value and crown, except leaf area traits. Genetic correlation among leaf chlorophyll SPAD value, leaf area and crown were not observed. Based on phenotypic and genetic variation of growth traits, the early index selection of excellent provenances / families was carried out with tree height, DBH, ground diameter, leaf chlorophyll SPAD value, leaf area and crown diameter (measured in 2018). The provenance index coefficients of tree height, DBH, ground diameter, leaf chlorophyll SPAD, leaf area and crown diameter were 0.78, 0.54, 0.48, 0.11, 0.05 and 0.87, respectively. The average aggregation index of provenance was 17.62±1.88. Two excellent provenances (No.3 and No.8) were selected as their aggregation index of multiple traits was greater than the average value+1 standard deviation (mean+SD = 19.50). The average genetic gain of tree height, DBH and DBH for excellent provenances was 43.06%, 101.46% and 115.84%, respectively. Six excellent families were selected according to the index of family aggregation (11.81) constructed based on population mean values. The selection rate was 13.03%. The genetic gains of tree height, DBH, ground diameter, leaf chlorophyll SPAD value, leaf area and crown diameter of the selected population were 6.87%, 6.54%, 6.77%, 2.62%, 3.50% and 9.43%, respectively. 【Conclusion】 There are abundant provenance and family variations among the early growth characters for D. tonkinensis. The genetic control of growth and wood properties at provenance and families were observed above moderate intensity. The highly genetic variation of the introduced germplasm ofD. tonkinensis provided a basis for genetic breeding, and this can be further used for genetic improvement of D. tonkinensis.
