Non-structural carbohydrate and water dynamics of Moso bamboo during its explosive growth period

Newly sprouted culm (culm(_new)) of Moso bamboo can complete its height growth within 1 or 2 months without growing any leaf. This explosive growth without enough leaf photosynthesis may rely heavily on external carbon input, such as carbon storage in the rhizomes or culms from the nearby mother culms (culm(_mother)). However, the existing studies have not explored the role of new photosynthesized carbon by the nearby culm(_mother) and the corresponding water dynamics. Therefore, this study monitored non-structural carbohydrates in the culm(_mother) and water transfer between the culm(_new) and their attached culm(_mother) in a 3-month experiment. Nine pairs of newly sprouted and attached culm(_mother) were categorized into three groups with three different treatments, that is, (1) control without any treatment, (2) cutting off rhizomes between the culm(_new) and culm(_mother) (Treatment I), and (3) removing all leaves of culm(_mother) based on the Treatment I (Treatment II). The differences between non-structural carbohydrates of the culm(_mother) in the control and treatment I were defined as transferred carbohydrates transferred outward from culm(_mother). The difference between treatments I and II was defined as newly photosynthesized carbohydrates of the culm(_mother). Before the culm(_new) leafing, there were significant transferred carbohydrates and newly photosynthesized carbohydrates from the culm(_mother). In contrast, the carbon transfer became fewer after leafing. At the same time, the sap flow direction in the rhizomes indicated water flows from culm(_new) to culm(_mother) during the day and vice versa at night of the culm(_new) at the pre-leafing stage. These findings may suggest that the explosive growth of the culm(_new) relies on both previous carbon storage and newly photosynthesized carbohydrates, and the carbon transfer may be coordinated with water transportation between the culms. Further study may pay attention to the potential support from the overall network of the bamboo stand or groves.