Abstract: Chlorophyll and carotenoids measurement by dimethyl sulfoxide (DMSO) and acetone extractions are two typical and popular methods used in plant ecophysiological research. However, few studies on the comparability between these two methods have been carried out. To answer this question, the contents of pigments in leaves and young branches of 19 woody species were measured in this study and we found the following conclusions. Firstly, chlorophyll a (Chla), Chlb and total chlorophyll contents measured by the DMSO method were much higher than those measured by the acetone method, however, the result of Chla/b ratio was slightly affected. Contrarily, carotenoids contents measured by the acetone method were much higher than those measured by DMSO method. Direct comparison of these data will make serious bias; Secondly, both chlorophyll data and carotenoids data measured by these two methods were significantly linearly correlated. Thus, it is possible to use these linear relations to make data correction in comparative studies; Thirdly, unit differences also affect the data correlations of these two methods. When using the unit of fresh mass, the correlation was much higher than that unit of surface area; Fourthly, the influences of these two methods on the data precision differed between leaves and branches. In the case of branches (low chlorophylls), two methods give slightly difference. However, the difference was much significant in the case of leaves (high chlorophylls). The possible reason may attribute to the extracting efficiency of DMSO is much higher than acetone. Finally, spectrophotometer precision (0.1 and 1 nm) were strongly affected the result of different pigments measured by DMSO method. The 0.1 nm spectrophotometer produced 15%~33% higher concentration of Chla, Chla+b and carotenoids, but a 4% lower concentration of Chlb although all the correlation coefficient R² of two equipments were over 0.99. Our above methodological findings may provide a basis for pigments comparison in physiological field.

Key words: leaves, branches, chlorophylls, carotenoids, methodological comparison