Allelopathic Effect of Black Pine(Pinus thunbergii)Needles and Litter on Four Cover Plants

摘要

Black pine(Pinus thunbergii)is one of the main afforestation species in the sandy coast and the preferred tree species for landscape green in northern China.Allelopathic activity could be one of the reasons of the sparse vegetation under black pine forests.To explore the allelopathic potential of P.thunbergii,the effects of litter and fresh needles were evaluated against the common cover plants seeds and seedlings,i.e.Tateges erecta,Orychophragmus violaceus,Ophiopogon japonicas and Trifolium repens.The results showed that P.thunbergii possessed allelopathic potential to the accompanying plants.Increasing concentrations of aqueous extracts of needles and litter affected target plant development in different levels.Growth and germination inhibition were directly related to the extract concentrations of needles or litters.Fresh needles played a more important role in the inhibition to target plants than litter because of the less germination rate and biomass in the same concentration.In addition,the adaptability of cover plants to the allelopathic effects of P.thunbergii is obviously different.The sensitivities of the four cover plants to the allelopathic effects of P.thunbergii were in order of T.repens>O.japonicas>O.violaceus>T.erecta.Therefore,T.repens is least suitable for concomitant planting with P.thunbergii,and T.erecta is the most suitable,with other two plants in between in landscape configuration.