The water transport profile of Phyllostachys edulis during the explosive growth phase of bamboo shoots

Abstract

The new bamboo shoots do not generate leaves during the explosive growth period. Thus, they cannot perform photosynthesis during this period. The water use profile and control mechanism of water transport during the explosive growth period of Moso bamboo (Phyllostachys edulis) shoots are still unclear. This study applied thermal dissipate probe (TDP) technology for monitoring the sap flow rate (Fs) dynamics in Moso bamboo during explosive growth phases (2008¬2010). We investigated the underlying mechanism of rapid growth by analyzing the water transport profile in a system consisting of the stem, rhizome, and shoot. We found that the Fs increase during explosive growth periods was consistent with the grow rate of bamboo shoots, the explosive growth phase was controlled by the sap flow. Water flew mainly from the rhizome toward the stem before shoot development but switched to the shoot during shooting. The water flow direction shifted from the stem and rhizome to the new shoot, ensuring the water and nutrient transport needed for growth and metabolisms. Diurnal Fs variations during growth periods followed a typical “single-peak” pattern with a daytime peak, resulting in a higher growth rate of bamboo shoots during the daytime. On the annual scale, Fs has an on-off-year alternation with higher on¬year rates than off¬year rates, which was consistent with the regulation of the bamboo shoot emergence. Correlation analysis found that leaf area index variations could explain the observed Fs variations of 95–97%. Economic bamboo forest management should ensure sufficient water supply during the explosive growth period of bamboo shoots. Further research should strengthen our knowledge about the hydraulic characteristics of Moso bamboo during explosive growth periods to ensure efficient forest management.