Competitive characteristics related to nitrogen utilization and calla lily growth in rubber-calla lily intercropping systems

In this study, we analyzed the interspecific competitive relationships and their effect on the growth and nitrogen (N) utilization characteristics of calla lilies in rubber-calla lily intercropping systems using root barrier and 15N tracer techniques. Our results showed that intercropping significantly inhibited calla lily growth and reduced nitrogen uptake. Nitrogen utilization efficiency was also reduced in the individual parts of calla lily plants, as well as on a whole-plant basis, as a result of competition with rubber trees for nitrogen. Furthermore, nitrogen uptake by calla lily from fertilizer was lower than that from soil, and the percentage of nitrogen taken up from the fertilizer and the nitrogen utilization efficiency calculated by the tracer method were lower than those calculated using the difference method. Our results demonstrated that there two ways in which interspecific competition for nutrients between calla lilies and rubber trees can be mitigated: (1)calla lilies use adaptive strategies (such as increased root length, increased root numbers, and enhanced dry matter allocation to roots) to maximize their nutrient access and (2) N fertilizer application.