Clonal integration driven by source-sink relationships is constrained by rhizome branching architecture in a running bamboo species (Phyllostachys glauca): A 15N assessment in the field

Source-sink relationships and branching architecture are two determinants of clonal integration, but their joint effects on resource translocation are still unclear. Our aim was to elucidate the pattern and mechanism of resource translocation controlled by source-sink relationships and branching architecture. We conducted a N-15-tracing experiment in six plots of a running bamboo, Phyllostachys glauca, in the field. The immature ramets and mature ramets were defined as strong sinks and weak sinks according to their sink strength, and the territories of integrated ramets were classified into zero-barrier zones and barrier zones considering rhizome branching architecture. The translocation of N-15 for all ramets showed a logarithmic pattern over time with a peak around the fifth week after labelling. Spatially, N-15 was exported first to ramets in zero-barrier zones within three days and then to ramets in barrier zones within three weeks. Ramets in zero-barrier zones had a significantly higher translocation intensity (1653.2 parts per thousand), speed (1.95 m/day) and amount (39.9 mg kg(-1)), and a shorter translocation time (three days) than ramets in barrier zones (61.3 parts per thousand, 0.86 m/day, 2.3 mg kg(-1) and 1.4 weeks, respectively). In zero-barrier zones, translocation intensity and amount in immature ramets were 6.7 and 3.4 times greater than those in mature ramets, respectively. In barrier zones, translocation traits (intensity, speed, time, amount) of immature ramets and mature ramets were similar. In addition, distance did not affect nitrogen translocation pattern or the effects of rhizome branching architecture and source-sink relationships on nitrogen translocation. The nitrogen translocation was mainly confined in zero-barrier zones by rhizome branching architecture, where source-sink relationships worked. In the clonal integration of P. glauca, source-sink relationships are the driving forces, while rhizome branching architecture acts as a flow restrictor. The results provide implications for spreading control and fertilizer applications on running bamboos.

Automated summary

The study found that ramets in zero-barrier zones exhibited higher intensity, speed, and amount of nitrogen translocation compared to ramets in barrier zones. Immature ramets had significantly greater translocation intensity and amount than mature ramets in zero-barrier zones, while translocation traits were similar for both in barrier zones. Distance did not impact nitrogen translocation, which was mainly confined to zero-barrier zones by rhizome branching architecture.