Allelopathic Effect of Volatiles of Eupatorium adenophorum on Seed Germination and Seedling Growth of Pinus Yunanensis

In order to know the allelopathy of stem and leave volatiles of Eupatorium adenophorum,Pinus yunnanensis seeds were treated by fresh stem and leave of E.adenophorum of different quality in transparent airtight boxes,the concentrations are high concentration(0.069 4 g/cm3),middle concentration(0.023 1 g/cm3)and lower concentration(0.007 7 g/cm3) respectively.The results showed that the volatiles had a significant influence on seed germination process of P.yunnanensis,the day on which seeds started to germinate,the day on which germination pinnacle came,the day on which germination number descended significantly,all delayed with the increase of concentrations,seed germination numbers of the day at the germination pinnacle also delayed with the increase of concentrations,so the germination process curves became gentle with the increase of concentrations,and nearly became a beeline at high concentration.The tendency of the effects of the volatiles on seed germination(seed germination rate,seed germination potential,seed germination speed) and seedling growth(fresh weight,dry weight,radicle length,hypocotyl length)of P.yunnanensis was similar,showing a rule that high concentration had a negative effect on seed germination and seedling growth,the negative effect became weaker and weaker with the descent of concentrations.E.adenophorum was widely distributed on the ground under P.yunnanensis forest,and might influence natural regeneration and growth of P.yunnanensis by allelopathy.