Seasonal changes of endogenous soluble sugar and starch in different developmental stages of Fargesia yunnanensis

Abstract

The endogenous soluble sugars and starch are the main carbohydrates accumulated in bamboo culms and the seasonal changes of their contents are also related to the bamboo phenology. In this study, it is observed that the dormancy phase of new Fargesia yunnanensis culms continued as long as 6 months from November to next May. The time interval for the sugar storage between the branching and leafing stage and shooting stage is relatively short. Moreover, the branching and leafing stage overlapped the shoot buds formation stage. Starch granules were depleted when the branching and leafing stage commenced, but then were accumulated before the shooting stage. The endogenous soluble sugar content in 2- and 3-year-old culms decreased during the branching and leafing stage, but increased before the shooting stage, and then decreased after the shooting stage. In shoots, the endogenous soluble sugar and starch contents increased and decreased with culm elongation, respectively. Starch granules were accumulated more in nodes than in internodes in un-elongated internodes. Shoot buds and shoots are the main sink tissues for sugar storage in the whole clumps. The bamboo clumps should be fertilized and irrigated before and after the branching and leafing stage and shooting stage. The late autumn is the best season for the culm harvest.