小蓬草水浸液对2种花卉种子萌发及幼苗生长的化感作用北大核心CSCD

为揭示入侵杂草与草本花卉之间的竞争关系,以入侵植物小蓬草为供体材料,常用的花卉波斯菊、观赏油菜为受体材料,研究了小蓬草根、叶水浸提液对受体植物种子萌发、幼苗生长、抗氧化酶活性(SOD、POD和CAT)以及丙二醛(MDA)含量的化感效应差异。结果表明,(1)小蓬草浸提液对受体植物的种子萌发均具有显著化感效应,基本表现为“低促高抑”的趋势,且波斯菊、观赏油菜的种子萌发率在根、叶浸提液浓度为25 g/L时最高,在浸提液浓度为100 g/L时最低。(2)小蓬草浸提液对受体植物幼苗上下胚轴生长具有“低促高抑”的浓度效应,且浓度越大抑制作用越显著。(3)在小蓬草根、叶浸提液处理下,观赏油菜的SOD和POD活性大多显著高于对照,波斯菊SOD和POD活性则大多显著低于对照;波斯菊、观赏油菜CAT活性整体呈先缓慢升高后降低的趋势。(4)波斯菊幼苗MDA含量随小蓬草根、叶浸提液浓度的增加均呈现逐渐升高的趋势,并大多高于对照水平,而观赏油菜幼苗MDA含量随着根浸提液浓度增加而逐渐升高,却随着叶浸提液浓度的增加而降低,但大多显著低于对照水平。研究发现,小蓬草浸提液对2种花卉种子萌发和幼苗生长均表现出“低促高抑”化感作用,且综合效应强弱表现为观赏油菜大于波斯菊,根浸提液处理大于叶浸提液。     

Above‐ and Belowground Impacts of European Buckthorn (Rhamnus cathartica) on Four Native Forbs

Fast‐growing European buckthorn (Rhamnus cathartica) shrubs are aggressively invading woodlands in eastern and midwestern North America. Buckthorn casts dense shade, alters soil conditions, and may be allelopathic. We used greenhouse and field experiments to investigate above‐ and belowground effects of Rhamnus on four herbaceous species native to southern Wisconsin. In the greenhouse, we assessed how Rhamnus leaves and fruit affected seed germination and seedling growth relative to sugar maple (Acer saccharum) leaves. Fewer seeds of Eurybia macrophylla and Thalictrum dasycarpum germinated under Rhamnus leaves, and those that germinated were slowed. We planted seedlings of the four natives into four treatments at three sites in the field to assess how their survival, growth, and flowering respond to the separate and combined effects of light levels, buckthorn canopies, and buckthorn soils. Buckthorn consistently reduced native plant performance by diminishing survival, flowering, and growth in Thalictrum, survival and flowering in Eurybia, and flowering and growth in Symphyotrichum lateriflorum. Removing buckthorn canopies enhanced growth of these native species, but buckthorn soils separately inhibited growth at least as much (despite being more fertile). Buckthorn's impacts on native plants exceed effects attributable to light levels and soil fertility, suggesting allelopathy. Buckthorn reduced performance more in the uncommon species (Thalictrum and Eurybia) than the common species (Geranium maculatum and Symphyotrichum). As we do not yet know how long these inhibitory soil effects persist, we need additional research to learn how best to control buckthorn's impacts on native plant communities.     

Allelopathic potential of glucosinolates (mustard oil glycosides) and their degradation products against wheat

A number of glucosinolates and isothiocyanates were tested for their allelopathic potential against wheat. Most of the glucosinolates showed no activity against wheat, with the exception of glucobrassicin which was moderately active, as was sinapine thiocyanate. Isothiocyanates showed high activity against wheat germination and seedling growth. The most active compound, 2-phenethyl ITC completely inhibited wheat germination at 500 ppm. Allyl ITC showed high activity whereas other isothiocyanates tested were only moderately active. The data is discussed in relation to the possible use of some mustard species for effective weed control.