Effects of clonal integration on photochemical activity and growth performance of stoloniferous herb Centella asiatica suffering from heterogeneous water availability

摘要

Clonal integration allows translocation of water between interconnected ramets, improving fitness of clonal plants growing in heterogeneous water availability. However, few studies have been conducted to investigate the effects of clonal integration on physiological responses of clonal plants suffering from heterogeneous water availability. A greenhouse experiment was conducted by using clonal fragments of the stoloniferous herb Centella asiatica with two successive ramets. The basal ramets were grown in patches with 40% soil moisture (high water availability), while the apical ramets were grown in patches with 40% (high water availability), 20% (medium water availability) and 10% soil moisture (low water availability) respectively. Stolons between the basal and apical ramets were severed (clonal integration impeded) or retained intact (clonal integration allowed). Our results showed that clonal integration relieved negative impact of water deficiency on the apical ramets in terms of photochemical activity and growth performance. Clonal integration modified biomass partitioning both for the apical ramets growing in low water availability and the basal ramets growing in high water availability. In addition, significant cost of clonal integration was observed in terms of growth performance of whole clonal fragments. A possible explanation is that increased biomass allocation to root may reduce capturing of light energy, producing negative effect on biomass accumulation of the basal ramets under high water availability contrast between patches. The results suggest that the net benefit of clonal integration may depend on the contrast of resource availability between interconnected ramets.