Relative costs and benefits of clonal integration of Zoysia japonica under various N:P ratios

Clonal plants adaptively respond to abiotic stress, but to date little is known about under what circumstanses clonal integration is beneficial, or costly. To study the costs and benefits of clonal integration on clonal growth, we cultivated Zoysia japonica under three ratios of N:P (N:P ≈ 7, 14:1 and 21:1), and four types of stolon severing treatments (connected stolon CS, light severing LS, moderate severing MS, serious severing SS). The results showed that Z. japonica performed best at a low ratio of N:P (N:P ≈ 7:1). When the stolons were connected (CS), the growth of primary A-ramets, multiple-nodes and stolons benefited from clonal integration; however, the growth of primary B-ramets on the primary stolons, A and B ramets was significantly reduced (p < 0.05). In the moderate stolon severing treatment MS_7:1 (N:P ≈ 7:1), clonal integration appeared more cost effective than in all other treatments. On the whole, with increasing stolon severing intensity, the cost of clonal integration increased and the clonal growth of Z. japonica declined significantly. The pattern of biomass allocation may be useful for Z. japonica to adapt to the various environments, and clonal integration plays a significant role under adverse environmental conditions.