不同养分条件下密度对空心莲子草生长和光合特性的影响

为了理解在不同养分水平下密度对入侵植物空心莲子草（Alternanthera philoxeroides）的影响，设置了3种养分水平（低、中、高）和3种种植密度（低、中、高）对空心莲子草进行温室控制试验。结果显示，养分水平和密度均对空心莲子草的生物量和光合指标具有显著影响。中养分水平处理下的空心莲子草单株生物量和整盆总生物量在3种不同的种植密度下均最高，但其光合速率以及叶绿素含量在高养分水平处理最高。同一养分水平对比发现，空心莲子草光合速率均在中等种植密度的处理中达到最大。随着种植密度的增加，空心莲子草的光合作用和单株生物量会逐渐降低，但整盆的总生物量升高，这些特点可能会有助于空心莲子草发展成单优群落。本研究对理解空心莲子草及类似入侵植物的入侵机制具有重要意义。

Effects of planting density on the growth and photosynthesis of Alternanthera philoxeroides at different nutrient conditions

In order to reveal the effects of planting density on the performance of invasive plant under different nutrient conditions, a greenhouse experiment was conducted in which Alternanthera philoxeroides was planted at three population densities (low, medium and high) under various nutrient levels (low, medium and high). The results showed that both population density and nutrient level 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. The photosynthetic rate was the highest at medium population density under every nutrient level. The photosynthesis and 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 to form monodominant community. This study contributes to the understanding of invasion mechanism of A. philoxeroides and other similar invasive plants.