中文摘要：

植物化感作用是指植物通过向环境释放化学物质,对周围植物（包括微生物）产生直接或间接的有害或有利的作用（Rice,1984）。同种植物间的化感作用被称为自毒作用（Hegde et al.,1990）,自毒作用广泛存在于植物森林生态系统中（Zeng et al.,2008）.

英文摘要：

Schrenk spruce（ Picea schrenkiana）,a major tree species in the forest ecosystems of Xinjiang,plays an important role in water conservation. 3,4-dihydroxyacetophenone（ DHAP） is a principal autotoxic substance in P. schrenkiana needles as well as its litter,and the substance may contribute to P. schrenkiana natural regeneration. In this paper,we determined the change of endogenous plant hormones（ ZT、GA3、IAA and ABA） contents during seedling growth of P. schrenkiana with the ultra performance liquid chromatography（ UPLC）,and measured growth in radicle,plumule and fresh weight of the seedlings subjected to DHAP treatments,trying to explain physiological mechanisms of the autotoxic effects. The results showed that DHAP treatment had no significant effect on plumule growth of P. schrenkiana but had significant inhibitory effect on fresh weight（ The fresh weight treated with 0. 1 mmol ·L^- 1DHAP significantly increased in 10 d）. The impact of DHAP treatment on radicle elongation had a concentration effect in an order of： 5 mmol ·L^- 1 1 mmol·L^- 1 0. 1 mmol·L^- 1 control（ After 10 d,radicle elongation of 0. 1 mmol·L^- 1DHAP treatment groups increased significantly）. With DHAP concentration increased, the GA3concentration decreased, the ABA concentration increased,and the ratios of ABA / ZT、ABA / IAA、ABA /（ ZT ＋ GA3＋ IAA） increased. In 4- 6 d,after 5 mmol·L^- 1DHAP treatment,the IAA concentration increased greatly（ 1. 24^- 1. 70 times higher than that of control group）,which might inhibit the seedling growth. For 0. 1 mmol · L^- 1DHAP treatment group,after 10 d,the concentration of ZT and IAA increased,the concentration of ABA decreased,and the ratios of ABA / ZT、ABA / IAA、ABA /（ ZT ＋ GA3＋ IAA） decreased,which might cause the radicle elongation and fresh weight increasing rapidly. It is suggested that the change of contents and the ratios of endogenous plant hormones during the seedling growth caused by DHAP treatment might be the key factor inhibiting（ p