遮荫和氮养分对三裂叶蟛蜞菊生长、构件生物量分配和叶片PSⅡ功能的影响

To explore the responses of the alien invasive plant Wedelia trilobata to shading and nitrogen nutrients and its invasiveness, a pot experiment was conducted to study the effects of shading (mild shading - relative light intensity of 42%; severe shading - relative light intensity of 12%) and different nitrogen nutrients (0, 0.1, 0.2 and 0.4 g·kg~(–1)) on the growth, biomass allocation and leaf PSⅡ function of Wedelia trilobata. The results showed that: 1) The number of leaves, number of branches, total biomass and growth rate of plants under mild shading were significantly greater than those under severe shading; under the same shading condition, with the increase of nitrogen nutrients, the stem biomass ratio increased and the leaf biomass ratio decreased. 2) Severe shading reduced the actual photochemical efficiency (ФPSⅡ) and the apparent photosynthetic electron transport rate (ETR) of the leaves of Wedelia trilobata and had a certain damaging effect on the PSⅡ reaction center of the leaves; the effect on the maximum photochemical quantum yield (Fv/Fm) was not significant (except at the 0.2 g·kg~(–1) nitrogen level). 3) The effect of nitrogen nutrients on the PSⅡ activity of the leaves varied with the degree of shading. Under mild shading, the effect of nitrogen nutrients on the PSⅡ function of the leaves was small; under severe shading, with the increase of nitrogen nutrients, ФPSⅡ and ETR first increased and then decreased, and the change of Fv/Fm was not significant. 4) The interaction between light intensity and nitrogen nutrients plays an important role in the growth, competition and successful invasion process of the Wedelia trilobata population, and it is easy to successfully invade in habitats with sufficient light.

为探查外来入侵植物三裂叶蟛蜞菊(Wedelia trilobata)对遮荫和氮养分的响应及其入侵性,采用盆栽实验研究了遮荫(轻度遮荫-相对光强为42%;重度遮荫-相对光强为12%)和不同氮养分(0、0.1、0.2和0.4 g·kg~(–1))对三裂叶蟛蜞菊生长、生物量分配以及叶片PSⅡ功能的影响。结果表明: 1)经轻度遮荫的植物叶片数、分枝数、总生物量、生长速率显著大于重度遮荫;同一遮荫条件下,随氮养分的增加,茎生物量比增加、叶生物量比下降。2)重度遮荫降低了三裂叶蟛蜞菊叶片实际光化学效率(ФPSⅡ)和表观光合电子传递速率(ETR),对叶片PSⅡ反应中心有一定破坏作用;对最大光化学量子产量(Fv/Fm)的影响不显著(除0.2 g·kg~(–1)氮水平外)。3)氮养分对叶片PSⅡ活性的影响随遮荫程度而变化,轻度遮荫下,氮养分对叶片PSⅡ功能影响较小;重度遮荫下,随氮养分的增加, ФPSⅡ和ETR先上升后下降, Fv/Fm变化不显著。4)光强和氮养分的交互作用在三裂叶蟛蜞菊种群生长、竞争以及成功入侵过程中发挥着重要作用,在光照较充足的生境中容易成功入侵。