Addition of Phosphorus and Nitrogen Support the Invasiveness ofAlternanthera PhiloxeroidesUnder Water Stress

Coordination of plant functional traits with changes in the environment is helpful to understand the mechanisms underlying both invasiveness and adaptation of plants. Thus, to investigate the performance and functional traits in invasiveAlternanthera philoxeroides(Mart.), an experiment of water stress is conducted with different nutrient concentrations.Alternanthera philoxeroidesplants are grown under natural and nutrient soils and subjected to three levels of nitrogen (N) and phosphorus (P) solution: ambient P and N concentration (P-N-), P addition with an ambient N concentration (P+N-), and P addition with high N concentration (P+N+) in combination with three different irrigation water levels as 1) 100% irrigation, 2) 50% irrigation, and 3) 25% deficit irrigation. Based on results,A. philoxeroidesproduces significantly higher biomass in both soils under 100% irrigation with P+N- treatment and exhibits higher values of leaf area and root length. However, 25% irrigation with P-N- treatment in both soils exerts a significant negative effect on relative growth rate and root/shoot ratio ofA. philoxeroidesplants. Under 50% irrigation in soils with both P+N- and P+N+ treatments, high values of leaf nitrogen are recorded. Moreover, nutrient soil is more supportive toA. philoxeroidesthan natural soil.