The old age of Eucalyptus saligna Smith, at São Paulo state, by fiber dimensions

Abstract

The objetive of this study was to get some information about fiber length variation in the growth rings of Eucalyptus saligna, with 21 year old, which data could give the mature age of this plant at São Paulo States. Two disc from two plants were colected at the level of D. B. H. at Forest Experiment Station "Navarro de Andrade" at Rio Claro, in which there were stands of this species, which age was known. From each disc was take one sector of south side of the trunk and the surface was polished with the finality to identify the growth rings by macroscopic and microscopic observation. Since each sector had 21 growth rings and the age of the plants was 21 years old, it was possible to correlated the number of growth rings with the age of the plants. After that, each growth rings from 3 sectors of one plant was macerated in individual vials and 6 or 8 slides was prepared in which 5 fibers and 5 veessels was measured. The statistical analysis showed the following results: 1.º) The analysis of variance of mean fiber length in the 3 sectors point out that the value of residual error was praticaly the same. (See Table I). This make possible to analyse the data of both sectors together, and the analysis of variance for fiber length mean in the growth rings was significant at 1% leve of probability. (See Table II). By using the regression equation it was possible to determine the maximum of the fiber length among the 21 growth rings and also in which the mean value of "Runkel coefficent" reache the assintotic value. The maximum value or fiber length was reached at the 10th growth ring and Runkel coefficent reache between 14th and 15th growth rings in one plant and between 9th and 10th in other. (See Figure 1 and 2). These results led us to conclude that in São Paulo States the mature age in Eucalyptus saligna was reached at the 9th or 10th growth rings, that correspond to 9 or 10 years old.