Effects of planting density on the growth and photosynthetic characteristics of Alternanthera philoxeroides under different nutrient conditions

Density and nutrient level are important factors that might affect the growth of invasive plants. To reveal the effects of plant density on the performance of invasive plant Alternanthera philoxeroides under different nutrient conditions, a greenhouse experiment was conducted in which A. philoxeroides was planted at three densities (low, medium and high) under three nutrient levels (low, medium and high). The results showed that both planting density and nutrient levels had significant effects on the growth of the plant. The biomass of individual plant and all plants in one pot under medium nutrient level were the highest while the photosynthetic rate and total chlorophyll content were the highest at the high nutrient level. Under different nutrient levels, the photosynthetic rate was the highest at medium planting density. The biomass of single plant decreased with the increase of population density, while the total biomass in the whole pot increased with the increase of density. These characteristics might contribute to the invasion of A. philoxeroides and help the plant to form monodominant community.