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Yin Y.N.,Norwest Agriculture and Forestry University | Zhang W.H.,Norwest Agriculture and Forestry University | He J.F.,Norwest Agriculture and Forestry University | Hu X.J.,Norwest Agriculture and Forestry University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Tannin extract is one of the significant forestry chemical products. The main component of tannin extract is tannin. Tannin, which is an important chemical material for forestry, can be extracted from the organs of Quercus variabilis widely in China. To illustrate the variation of tannin content, the barks, shell buckets, fruits, roots, stems and leaves of 72 Q. variabilis trees from the four types were sampled based on different diameters at breast height were on the south slopes of Qinling Mountains in October 2012. The content of tannin in the organs were analyzed by UV spectrophotometry, and the influence of tree growth on the tannin content was detected by Pearson correlation and linear regression. The result indicated that there was a great variation between the individuals of the four types. Our aim is to provide an reference and experiment basis for the directive cultivation and effective utilization of Q. variabilis resources. It was showed concretely as follows. (1) The average tannin content of 2.31%-2.72% was found in the roots of the four types of Q. variabilis, as well as 1.31% - 1. 72% in the stems, 6.32%-6.89% in the leasves, 4.49%-4.92% in the branches and 8.17%-8.86% in the barks. The content of tannin in the leaves, branches and barks are much higher than that in the roots and stems obviously. Leaves, branches and barks were suggested as the major raw materials of tannin extract. (2) The significant difference of tannin content was observed among the different organs of the four types of Q. variabilis. In the leaves, branches and barks, the content of tannin ranged from high to low as the thick bark deep crack type, the thick bark shallow crack type, the thin bark deep crack type, the thin bark shallow crack type. The tannin content in the roots and stems of the four types ranged from high to low as the thin bark deep crack type, the thin bark shallow crack type, the thick bark shallow crack type, the thick bark deep crack type. Because of the tannin contents in the leaves, branches and barks with a high level, the Q. variabilis with the thick bark deep crack type was the best one in the four types for tannin extract. (3) The tannin content of the different organs in the four types augmented with the increasing DBH of the trees, and the top value was observed in the DBH of 20. 1-25cm. The DBH and the height of trees affected the tannin content positively. The suggestion is that the Q. variabilis with DBH above 25cm should be applied fully and efficiently for tannin extraction, or it should be priority for directive cultivation and special protection. Source

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