Non-structural carbohydrate was the main intermediate storage between photosynthesis and growth of plants， and played an important role in the growth and metabolism of plants. To explore the distribution and seasonal variation of non-structural carbohydrates and the relationship between soluble sugar and starch in roots. The root sample of Larix gmelinii was collected from May to October in 2018， and the samples were divided into 1， 2， 3， 4， and 5 rank by root order method. The concentration of soluble sugar and starch were measured using the phenol-sulfuric acid method and enzymatic hydrolysis method respectively. The results showed that the concentration of soluble sugar was a significant difference between root order， month， and their interaction（P<0.001）. The concentration of soluble sugar in 1-5 orders ranged from 4.42%~14.90%， 4.35%~16.40%， 5.67%~19.70%， 5.91%~33.10% and 6.95%~37.80%， respectively. There was no significant difference in the concentration of starch among different root orders（P>0.05）. However， the concentration of starch was a significant difference among months（P<0.001）. It was ranged 23.36%~48.65% and decreased from May to July， and then increased， peaked in August， and there was no significant difference between October and May in 2018. The results could provide data for explaining the carbon metabolism and growth adaptation strategies of roots and understanding the internal structure and functional heterogeneity of fine root system.
%U https://bbr.nefu.edu.cn/EN/10.7525/j.issn.1673-5102.2021.04.003