摘要：

In plant configuration of landscaping,herbaceous plant is often inter-planted with ornamental tree species.But unreasonable plant collocation may reduce the effectiveness of afforestation for the inhibition effect of tree on the growth of understory,and further more affect the greening effect.Camphor(Cinnamomum camphora) is widely planted in landscaping accompanying herbaceous plants including morning glory(Pharbitis nil).But camphor was reported to have allelopathic effect on its adjacent plant,therefore correct selection and collocation of plants has important significance to obtain good greening effect.This research aimed to study by a pot experiment the effects of decomposing leaf litter of Cinnamomum camphora on the growth,phenological traits of Pharbitis nil,as well as modification of these effects by nitrogen application.Three application rates of C.camphora leaf litter including 25,50 and 100 g/pot(denoted by L25,L50 and L100,respectively)and a control(CK) were implemented.Nitrogen application began on the 34 th d of decomposition,with 0.39 g urea being divided into three equal portions and added continuously to each pot.The results showed that(1) The height,basal diameter,leaf area and biomass production of Pharbitis nil were all inhibited sharply by exposure to the leaf litter,being decreased by32.85%-83.78%,5.23%-23.00%,30.31%-58.47%,and 40.34%-84.54%,respectively,with the inhibition effect increasing both in intensity and stability with the increase of leaf litter.Such inhibition effect was obviously alleviated by exogenous nitrogen application.(2) The flowering dynamics of Pharbitis nil was greatly impacted by the leaf litter,with the flower initiation 2.5-10.0d later and the flowering duration 6.3-11.4 d longer compared to the control.Although the leaf litter-treated plants exhibited more(0.5-3.3) flowers than the control,their quality decreased,and the hundred-grain weight of the seed decreased with the increase of leaf litter.However,the differences among treatments in the reproductive parameters mentioned above reduced after nitrogen fertilization.The results indicated that leaf litter of C.Camphora has a great allelopathic effect on morphological and reproductive growth of Pharbitis nil,which may be attributed to the release of phototoxic substances during the decomposition process.

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