替代牧草对黄顶菊生物量分配及光合作用的影响

选用高丹草、沙打旺两种牧草对入侵植物黄顶菊进行生物替代,比较不同替代处理中黄顶菊的生物量分配和光合特性的差异以验证替代效果。结果表明:替代调控明显地影响了黄顶菊的生物量积累并且改变了其分配格局;替代处理区的各生物量指标均显著低于对照区;与黄顶菊单种对照相比,沙打旺和高丹草中的黄顶菊总生物量分别下降了90.2%、94.2%;沙打旺中的黄顶菊和高丹草中的黄顶菊叶生物量比升高,而根生物量比、支持结构生物量比、根冠比降低,显示黄顶菊在替代处理下倾向于增加光合同化器官面积。替代处理下的黄顶菊光合作用均受到显著影响,净光合速率Pn显著下降,其中高丹草中的黄顶菊的Pn仅为2.15 μmolCO2·m-2·s-1。试验结果显示,在替代条件下限制光合的主要因素是非气孔限制因素,即导致黄顶菊光合作用大幅下降的原因是替代牧草遮阴作用引起的光能供应的不足。可塑性指数分析表明,黄顶菊具有较高的表型可塑性,显示其对逆境条件较强的适应性与入侵能力。替代措施能抑制黄顶菊的生物量积累与繁殖,影响其光合生产力,具有较好的防控效果。

Effects of replacement control with forage species on the biomass allocation and photosynthetic characteristics of Flaveria bidentis

Two native forage species (Sorghum bicolor × Sorghum sudanense and Astragalus adsurgens) were chosen to replace and control the exotic invasive plant Flaveria bidentis, and a field experiment was conducted to examine the effect of the replacement control with the two forage species on the growth and physiological characteristics of F. bidentis. The replacement control suppressed the growth and reproduction of F. bidentis effectively. Compared with that of monoculture F. bidentis, the total biomass of F. bidentis mixed cultured with A. adsurgens and S. bicolor × S. sudanense was decreased by 90.2% and 94.2%, respectively. Except for leaf biomass ratio, all the other biomass indices of F. bidentis in the replacement treatments decreased by more than 90%. The flower mass ratio of F. bidentis decreased significantly in A. adsurgens replacement treatment but increased in S. bicolor × S. sudanense replacement treatment. In the two replacement treatments, the net photosynthetic (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), and chlorophyll content of F. bidentis all had a significant decrease, and the Pn of F. bidentis in S. bicolor × S. sudanense treatment was only 2.15 μmol CO2·m-2·s-1. The results revealed that under the replacement control with the forage species, insufficient light supply limited the carbon assimilation of F. bidentis. Plasticity analysis showed that F. bidentis had higher phenotypic plasticity, and the phenotypic index of flower mass ratio reached up to 0.91, indicating the high invasive potential of the invasive plant. It was suggested that field replacement control could realize a win-win situation of economic value and ecological benefits.