| Picea schrenkiana is the endemic species in mountains of Asia and Middle Asia, is the most important zonal forest vegetation in Tianshan Mountains. It only distributes in Xinjiang. Distributing region mainly lies in northern slope of Tianshan Mountains, and a small quantity of Picea schrenkiana distribute in southern slope of Tianshan Mountains and northern slope of western part of Kunlun Mountain. With the increasing of forest product in economical construction and the accretion of disturbance intensity due to all kinds of economical action,we can see from history and realism of formation and development of problem that the problem of nature regeneration has became more serious in limited free fire period during forest nature restoration. Based on this problem, many studies on light, water and nutrient which saplings need have been researched. But we can see from the results and effects of study that it still needs a long time to solve this problem. Therefore, on the basis of the hypothesis of "the autotoxicity of Picea schrenkiana results to natural regeneration failure", using bioassay method, this research studied effects of the different concentration aqueous extracts from the needles of Picea schrenkiana on its seed germination and seedling growth. And this research was experimented on the premise of simulating the circumstance of the Picea schrenkiana seed germination and seedling growth in the artificial climatic cabinet. Furthermore, the changes of plant endogenous hormone were measured using Ultraviolet absorption approach during the period of its seed germination and seedling growth. The results as following:In aspect of the bioassay of Picea schrenkiana autotoxicity, the results showed that the aqueous extracts from the needles of Picea schrenkiana has autotoxicity on seed germination and seedling growth of Picea schrenkiana under two different temperature conditions (①photoperiod 20℃, 16h, dark cycle 15℃, 8h;②The photoperiod 15℃, 16h, the dark cycle 10℃, 8h). In bioassay, seed germination was promoted using lower concentration aqueous extracts, and seed germination was significantly restrained using higher concentration aqueous extracts. And the higher the concentration was, the more significant the inhibition was. In the temperature conditions of 15～20℃, the seed germination was promoted when the concentration of aqueous was 0.05gDWml-1 or below.But the seed germination was markedly inhibited when the concentration of aqueous was 0.1gDWml-1, and the inhibition rate of seed germination is up to 21.2%. Under the same concentration, the inhibition rate of root length and shoot length were 34.1% and 51.3% respectively. In the temperature conditions of 10～15℃,the seed germination and seedling growth was markedly inhibited when the concentration of aqueous was 0.1gDWml-1, and the inhibition rate of seed germination and root length are up to 28.6% and 32.0% respectively. Under the same experimental condition, shoot length was markedly inhibited, and the inhibition rate was 40.8% when the concentration of aqueous was 0.2gDWml-1. Besides, dry weight was accelerated as using the needles aqueous extracts. Wet weight was markedly inhibited when the concentration of aqueous was 0.2gDWml-1.In aspect of the physiological mechanism of Picea schrenkiana autotoxicity, the results using Ultraviolet absorption approach analysis showed litter aqueous extracts inhibit SOD activity whereas needle aqueous extracts promote it during the process of seed germination and seedling growth. Needle aqueous extracts inhibit SOD activity under the temperature of 15~20℃, but promote it under the temperature of 10~15℃during the process of seed germination, however, the effect of litter aqueous extracts on SOD activity reverse the needle aqueous extracts. In addition, it mainly indicates that litter and needle aqueous extracts inhibit POD activity while mainly inhibit CAT activity under the temperature of 10~15℃, and promote CAT activity under the temperature of 15~20℃during the process of seed germination and seedling growth. SOD and POD activity increase with the rise of temperature during the process of seed germination and seedling growth. CAT activity increase with the rise of temperature during the process of seedling growth while it is reverse during the process of seed germination. Three kinds of protective enzymes cooperate with each other which scavenge free radicals and activated oxygen that is produced during the process of seed germination and seedling growth. It weakens the harm from free radical and promotes seed germination and seedling growth. Litter and needle aqueous extracts promote PAL and amylase activity under the temperature of 15~20℃while inhibit it under the temperature of 10~15℃during the process of seed germination and seedling growth. The lower the temperature is, the higher the PAL and amylase activity is. Phenylpropanes metabolism is activated, and the enzymes reduce injury to seed germination. It indicates that different autotoxins are contained in the litter and needle aqueous extracts which change with environment. Some autotoxin may directly destroy structure and function of enzyme, hamper protein synthesis, thus affecting cell division and elongation which make plant growth and development stifled. Some autotoxin may destroy structure and function of cell membrane, then destroy chondriosome and chloroplast, and eventually inhibit seed germination and seedling growth, or even make it died.
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