Study On Correlation Between Growth Strain And Lignin Deposition In Three Eucalyptus

The mainly materials used in this study are Eucalyptus urophylla × E. grandis, E. urophylla and E. pellit. Their growth strain was measured by strain gauge. The growth strain value of samples which were made into microsection were higher than 900 and less than 400 respectively. Then the change of lignin content in differentiating fibre and vessel as well as different morphologic region in matured fibre and vessel was observed by light microspectrophotometer couped with Maule and Wiesner reaction. According to result, the relations between the change of lignin content and growth strain are as following:A comprehensive research was conducted on eucalyptus trees from three plantation species, including E. urophylla × E. grandis, E. urophylla and E. pellita, grown in south of China. Growth strain was measured on standing trees. The analysis results in this paper showed that: 1) There were highly significant differences in the mean surface longitudinal growth strain (SLGS) of standing trees among different species. 2) E. urophylla had the lowest growth strain level in all three species tested. 3) The mean SLGS of standing trees distributes between 450 × 10^-6600 × 10^-6 mainly at 1.3m height.The results of lignin research by light microspectrophotometer couped with Maule and Wiesner reaction are as following: 1) The special absorbance values are 510nm and 515nm in fibre cell and vessel after Maule reaction and Wiesner reaction, respectively. 2) After Maule reaction, the change trend of Syringlpropane lignin content is more tempered in the species of low growth strain than high growth strain as development of differentiating fibre cell forward mature cell. After Wiesner reaction, the change trend of guaiacylpropane lignin content has the similar trend as Maule reaction. Moreover, the cell numbers in the specials of high growth strain are relatively less than low growth strain when in the same differentiated stage. 3) Syringlpropane lignin and Guaiacylpropane lignin appeared in the differentiated stage of S₁ in fibre cell and vessel of Eucalyptus urophylla × E. grandis, E. urophylla and E. pellit. In fibre cell, the species of low growth strain haslower Syringlpropane lignin and Guaiacylpropane lignin content than the species of high growth strain, hi vessel, it has the similar result as in fibre cell.But the development of vessel was restrained in Si and S2 differentiated stage in Eucalyptus urophylla x E.grandis and E. urophylla of high growth strain. 4) Different morphologic region in matured fibre and vessel have different Syringlpropane lignin and Guaiacylpropane lignin content in three species. In fibre cell, Cell corner has the most lignin content, then middle lamella, S2 layer has the least lignin content.In vessel, Si layer, S2 layer and S3 layer almost have the same Syringlpropane lignin and Guaiacylpropane lignin content. But in S2 layer of differentiating cell, Syringlpropane lignin content is less than Si layer, which have the almost same content as S3 layer. Guaiacylpropane lignin content in S2 layer is higher than the other two layer.