| Schima superba Gardn.et Champ. is an important constructive and dominant species of the subtropical evergreen and broadleaf forest in southern China. In this study, genetic improvement of S. superba was researched in different ecological regions in Jiangxi Province. We carried out the test of seed quality and Seedling growth characteristics of S. superba. Furthermore, the geographical provenance variation was explored after 8 years of planting comparative experimental study. The study showed the results as follows.The first test of seed quality of S. superba was carried out in 2001. The result showed that there were abundant variations with the seed of S. superba and very significant difference among different provenances in thousand kernel weight and germination percentage. The average thousand kernel weight and germination percentage were 5.56 g and 17.28% respectively. The maximal thousand kernel weight was 2.3 times as much as the minimal one and the best germination percentage was 195 times as much as the worst one.The growth indexes of different provenances of S. superb were measured in this study. The provenances showed significant differences in height, ground diameter and dry biomass. Meanwhile, the high broad heritability was observed between provenances of S. superb. The tree height of Anhui Taiping provenance, Jiangxi Anfu provenance and Guangdong Kaiping provenance showed the same regularity and changed from slow growth, moderate growth, rapid growth, slow growth to growth stopped finally. The fast growing periods of height appeared between Augest to September. Latitude was significantly negatively correlated with the height and ground diameter, which indicated the provenance selection could achieve better results.There were very significant differences in DBH,height and volume of different provenances of Schima superb., and broad sense heritability respectively varied from 0.4778 to 0.7859,0.6840 to 0.7621 and 0.4943 to 0.8928, which indicated the three traits are controlled by the strong genetic factor.In addition, interaction between site and provenance were significant (P<0.01)。According to the growth traits of three sites, the average high, DBH and volume of S. superb at the age of 8 years at Xinfeng are 3.39cm,4.27m,0.0025m3 respectively, which increased by 42.4%,54.2%,178% as compared to Yongfeng, and 50.7%,117.9%,316.7% as compared to Dexing, respectively.We selected eleven good provenances which were most effective in different ecological regions in Jiangxi Province. The four provenances which effective in southern of Jiangxi province were Guangdong Kaiping, Hunan Chalin, Jiangxi Anfu and Zhejiang Longquan. The average tree height, DBH and volume of the four provenances were 4.58 m, 3.69 cm,0.0031m3 respectively which had average expecting genetic gains above 12.53%, 14.30%,36.71% and average real gains above 7.21%,8.92%,25.00% respectively. The six provenances which effective in middle of Jiangxi province were Guangdong Wengyuan, Fujian Wuping, Hunan Hengyang, Jiangxi Longnan, Jiangxi Xinfeng and Zixi. The average tree height, DBH and volume of the six provenances were 2.77 m,2.35 cm 0.0009m3 respectively which had average expecting genetic gains above 5.53%,10.40%,22.74% and average real gains above 8.09%,16.78%,37.36% respectively. In addition, We selected two provenances, i.t, Guangdong Kaiping and Jiangxi Guixi, which were most effective in northeast of Jiangxi province. The average tree height, DBH and volume of the six provenances were 2.34 m,2.36 cm,0.0008m3 respectively. The average expecting genetic gains of the two provenances increased 14.75%,2.11% and 12.36% compared with contrast, respectively, and the average real gains increased 19.36%,4.42%,25.00% respectively.Thirty-four provenances were divided into three groups by clustering analysis: Southern, Central and Northern provenance regional. Southern provenance regional included south-central and northwestern of Guangdong and southern of Fujian. Central provenance regional included Jiangxi, northern of Guangdong, Fujian, Hunan and Southwestern of Zhejiang, which is large areas of central part China's subtropical. And, Southeastern Anhui, north Zhejiang and northwest Hunan belonged to the Northern provenance regional. Furthermore, Central provenance regional included East and west sub-regionIn this study, we probed into the reasons that cause the growing differences between provenances from the perspective of photosynthetic parameters. Photosynthetic parameter determine tree growth rate to some extent. Based on modified rectangular hyperbola model to calculate photosynthetic parameters such as maximum net photosynthetic rate, light compensation point and light saturation point, our research tried to evaluate the adaptive capacities of different S. superba provenances (Guangdong Kaiping, Anhui Taiping and Jiangxi Yongfeng), and offer scientific support in order to screen proper S. superba provenance species for forestation. Our results showed that Guangdong Kaiping made its light saturation point and compensation point low to adapt light period in relative high latitude region (Yongfeng county, Jiangxi). In addition to high apparent quantum yields and maximum net photosynthetic rate, it made Guangdong Kaiping grew most rapidly. This result was in accord with actual condition that Guangdong Kaiping had the most rapid height growth rate. Anhui Taiping had relative high light saturation point and compensation point, and also had good adaptive capacity of light period in relative low latitude region (Yongfeng county, Jiangxi). However, Anhui Taiping's apparent quantum yields and maximum net photosynthetic rate were lowest, consequently its height growth rate was lowest. Jiangxi Yongfeng, as a local provenance species, had relative high apparent quantum yields and maximum net photosynthetic rate. It leaded to rapid height growth rate of Jiangxi Yongfeng, but its growth rate was lower than that of Guangdong Kaiping due to high dark respiration consumption. In the three S. superba provenance species, Guangdong Kaiping had strong adaptive capacity of local study region (Yongfeng county, Jiangxi) and growth potential. |
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