两种入侵植物凋落物对夏堇的化感作用

Allelopathic Effects of Two Invasive Plants Litter on Torenia fournieri

以假臭草(Praxelis clematidea)、三叶鬼针草(Bidens pilosa)为试验材料,采用温室盆栽试验方法,研究了2种外来杂草凋落物分解对夏堇(Torenia fournieri)植株生长的影响,以探明其凋落物在入侵园林绿地土壤中的化感作用。每种杂草分别设置L10(10g·盆^(-1))、L20(20g·盆^(-1))和L40(40g·盆^(-1))3个凋落物施用水平,以不添加凋落物为对照(CK)。结果表明:假臭草、三叶鬼针草的凋落物分解导致夏堇的株高、分枝能力、叶面积、生物量等性状指标大幅下降,尤其对分枝数量、叶面积和小花数量的抑制程度更高;并且随着凋落物量增加,其抑制作用更强,而假臭草的化感综合效应亦高于三叶鬼针草;夏堇的叶面积比、叶根比、比叶面积和平均相对生长速率显著降低,尤以假臭草的影响为甚,并且假臭草还能改变夏堇的生物量分配策略,根生物量比明显上升,茎生物量比则显著下降;与地下部根系相比,2种入侵杂草的凋落物分解对夏堇地上部茎、叶器官生长的化感效应更强,其生物量积累受抑制程度更高。

In order to explore allelopathic effects of Praxelis clematidealitter and Bidens pilosalitter in the invaded greenbelt soil,the effects of their litter decomposition on the growth of Torenia fournieri were examined by agreenhouse pot experiment.Three litter concentration levels of each weed were set as L10（10 g·pot^-1）,L20（20 g·pot^-1）and L40（40 g·pot^-1）,and no litter was added as control.The results showed that with the treatments of litter decomposition of the two exotic invasive weeds,the plant height,branching capacity,total leaf area and biomass of T.fournieri were declined dramatically,especially the inhibition effects on branch number,leaf area and flowerlet number.The allelopathic inhibition effects were generally enhanced with the increasing litter concentrations,and the allelopathic compound effect of P.clematidea was higher than that of B.pilosa.Leaf area ratio（LAR）,leaf area to root mass ratio（LARM）,specific leaf area（SLA）and relative growth rate（RGR）of T.fournieri were also significantly decreased,especially under P.clematidealitter treatments;moreover,the biomass allocation strategy of T.fournieri was changed by P.clematideatreatments,its root mass fraction（RMF）was increased obviously while its stem mass fraction（SMF）was decreased significantly.Compared with the underground root system,the allelopathic effects of litter decomposition of the two exotic invasive weeds on the growth of stem and leaf organs of T.fournieri were stronger,and the inhibition in their biomass accumulation was even higher.