Unequal nitrogen translocation pattern caused by clonal integration between connected ramets ensures necessary nitrogen supply for young Moso bamboo growth

Abstract

The rapid growth of young Moso bamboo ( Phyllostachys edulis ), a giant woody clonal plant, depends on consistent nutrient supply through clonal integration. However, the effects of clonal integration on nutrient translocation and allocation in Moso bamboo remain unclear. We established an in situ study model unit consisting of a young bamboo ramet, a mature bamboo ramet, and an interconnected rhizome to study nitrogen (N) translocation and allocation using the 15 N isotope labeling method. The results showed 15 N translocation was bidirectional between interconnected Moso bamboo ramets; however, more 15 N was translocated from the mature to the young ramet than vice versa in winter. The N translocation rate within the donor ramet was faster when the young was donor ramet, and N translocation rate from the donor to the recipient ramet was faster when young bamboo was the recipient ramet. Demand-driven source-sink relationships between connected ramets determined the net flow direction and speed of N translocation. Therefore, an “unequal N translocation pattern between the young and connected mature ramets” was proposed, in which N was preferentially translocated from the mature to the young ramet to meet its growth demand in winter. Our findings provide new insights into the underlying mechanism of Moso bamboo growth and N clonal integration network in Moso bamboo forests and could serve as a guide for precision fertilization in forest management. • N translocation was bidirectional with net flow from the mature to the young ramet. • N translocation within the ramet was faster when the young was donor or recipient ramet. • Demand-driven source-sink relationships determined net N flow direction and speed. • Unequal N translocation between young and mature ramets ensures young ramet growth.