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Water-soluble carbohydrates (WSC) are important substance in plant metabolism, major energy and nutrients materials for plant growth and development, and main storage form of vegetative. The most direct physiological index of plant senescence is reflected by WSC content. This paper compares the seasonal change of WSC contents of different age parts from Kalimeris integrifolia and Artemisia scoparia, which grew on Songnen grassland, tested through corrected phenol - sulfuric acid method, aimed at to discover the relationship between WSC contents and aging process of Compositae family. The main results are:From reviving stage to the fast growing period, the total content of WSC in the roots of the two Compositate plants showed similar reduction trends: A.scoparia decreased from 25.09% to 3.80%, K.integrifolia decreased from 4.77% to 3.86%.A steady increasing trend was showed from initial flowering stage to withering period in the root of K.integrifolia, from 3.86% to 10.61%.Throughout the whole growing season, among the average WSC contents of different modules of K.integrifolia, taproot ranked the highest, 8.77%, while root crown, basal stem were 5.53% and 5.48%, respectively. The taproot WSC contents of 1a-3a classes were 9.61%, 9.01% and 7.70%, respectively, the basal stem of 1a-3a classes were 4.07%, 6.49% and 6.05%, respectively, the root crown of 1a-3a classes were 6.30%, 5.80% and 4.51%, respectively. During the reviving stage, the WSC content in taproot, root crown and basal stem reached 9.90%, 3.93% and 0.48%, respectively. Significant differences were reached, showed that: the taproot was an important metabolic pool to store photosynthate, as well as an important source for stem and root crown. The WSC content in the taproot showed a decreasing trend during flowering and an increasing trend after flowering. During the reviving stage, the WSC content in the taproot was 1a>2a>3a. With the increasing in age class, the taproot of K.integrifolia showed an aging trend. The WSC content in basal stem accumulated gradually over growing period. In the late growing period, 2a class and 3a class continue increasing while 1a class decreased significantly. The WSC content in root crown did not change significantly on 3a class during reviving stage to flowering stage; during the fast growing period, 1a class decreased dramatically, which significantly differed from old age period; a trend of 1a>2a>3a was shown from flowering stage to the late period of growth.The WSC content in the root crown of A.scoparia during reviving stage and fast growing period were as follows: 1a class decreased from 25.99% to 1.77%. 2a class decreased from 25.03% to 5.89%, 3a class decreased from 14.74% to 3.94%, the metabolic activity slowing significantly as its age class increasing. The WSC content of the young root crowns were significantly higher than the 4a class in early reviving stage. The root crown of A.scoparia was aging as its age class increased. The average WSC content in the root crown was 8.71%,9.87% and 7.25%, respectively. The WSC content in the 2a class root of A.scoparia of different growth fixed number of year was as follows: biennial plant decreased from 35.68% to 2.07%, triennial plant decreased from 34.62% to 3.82%, quadrennial plant decreased from 25.11% to 7.35%, the average content was 12.36%,16.24% and 13.51%, respectively; the 3a class root was as follows: triennial plant decreased from 20.02% to 7.26%, quadrennial plant decreased from 22.62% to 6.85%, the average content was 12.47% and 13.83%, respectively. The WSC content in the root crown and root of A.scoparia showed a rapid decreasing trend during reviving stage and a continuous low level during fast growing period, which was mainly used for output, and the decreasing of WSC contents in the root crown and 2a class root of A.scoparia of biennial plant were the most, which greatly differed from quadrennial plant.From reviving stage to fast growing period, among the average WSC content of quadrennial A.scoparia, root crown ranked the lowest, was 7.25%; among the roots of aging classes, the 2a class ranked the lowest, was 8.49%, while the 3a class the highest, 13.83%, the 4a class closed to the 3a class, 13.50%. During the fast growing period, the WSC content in root crown was significantly lower than the root of old age, this indicated that the root of old age maintained the physiological function of nutrients accumulation and storage.
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