Abstract: Mikania micrantha is native to Central and South America. In 1919, M. micrantha appeared as a weed in Hong Kong, China. Since then, it has spread rapidly. At present, it can be found in many provinces of China, posing serious threats to forests, farmlands and orchards. It is one of the top 100 worst weeds in the world. A greenhouse experiment was conducted to examine the effects of clonal integration on the performance of the stoloniferous herbM. micrantha in habitats with heterogeneous light availability. The results showed that when light availability was heterogeneous, clonal integration increased biomass of ramets grown in patches with low light availability, reduced biomass of those grown in patches with high light availability, and did not significantly change the biomass accumulation of the whole clonal fragments. Clonal integration reduced the differences in root/shoot ratio among ramets, increased the difference in photosynthetic rate among ramets, and tended to increase the specific leaf area in the ramets grown under high light conditions. These results suggest that clonal integration did not affect the biomass accumulation of the whole clonal fragments of M. micrantha stolons grown under heterogeneous light conditions, but it would enhance the growth of the ramets grown under low light availability. Consequently, clonal integration would enhance the invasion of M. micrantha from open habitats to habitats with low light availability (e.g., forests, weed communities). Our results indicated that clonal integration is one of the important strategies for M. micrantha to adapt to habitats withheterogeneous light availability.

Key words: controlled-release urea, ammonia volatilization, fresh edible maize, nitrogen use efficiency, fertilization depth