Chinese Fir Autointoxication And Interspecific Allelopathy Between Chinese Fir And Its Associated Tree Species

Allelopathy is one of the most common phenomena in nature. Rice (1984) gave the following definition of allelopathy: "Any direct or indirect harmful or beneficial effect by one plant (including microorganisms) on another through the production of chemical compounds that escape into the environment". Allelochemicals were released by processes as volatilization, root exudation, leaching, and decomposition et alChinese fir (Cunninghamia lamcealata (Lamb.) Hook) spread through seventeen provinces in south China, which is recommended as the most important timber tree species in south China. The field investigation suggested that Chinese fir had poor establishment and low productivity, and would lead to soil degradation when grown after itself again. So, the bioassays seed germination was used to assays the effect of leaf, root, rhizosphere soil allelochemicals extracted by different solvent on Chinese fir seed germination and growth of seedling. Based on results of GC-MS, the effect of autointoxicational allelochemicals on seed germination and growth of seedling under different stress were done; Beside, lead to the Chinese-fir autointoxicationa, this paper also studied mutual relation between Chinese-fir autointoxicational allelochemicals and associated tree species's allelochemicals. This paper not only can research the mechanism of Chinese fir autointoxication, research Chinese fir reaction to autointoxicational allelochemicals and change of function of autointoxicational allelochemicals, reveal the nature chemical mechanism of Chinese fir autointoxication in eco-system of Chinese fir stand, but also can all settle the problems of poor establishment and low productivity, and would lead to soil degradation when grown after itself again, realize the sustainable management of Chinese fir stand. All of these have the most important theoretically referenced value and practical significance for low productivity of Chinese fir.(1) The aqueous extracts of leaf litter, half decaying leaf litter, fresh leaf, branch, bark, root of Chinese fir and the surface layer soil under chinese-fir pure stand affect the seed germination and the growth of bud of chinese-fir seed, that in high concentration of the above-mentioned aqueous extracts, seed germination and growth of bud are inhibited significantly; That with the concentration decreasing, the inhibitory effects get weak, disapper and even turn into stimulating effects and that after polyvinyl pyrrolidone k-300(pvp) were added into above-mentioned aqueous extracts, the inhibitory effects become weaker significantly.(2) Different concentrations of leaf and branch aqueous extracts had different effect on growth of Chinese fir seedling. The result showed that the high concentrations of leaf extracts had inhibitory effect on growth, index of photosynthesis and index of respiration of Chinese fir seedling the biomass of Chinese-fir seedling treated with leaf and branch aqueous extracts after six years were decreased, the higher the concentration was, the higher the inhibited effect was, and low concentration had positive effect on the leaf,bark, root,branch and stem biomass distribution, high concentration had positive effect on the litter biomass distribution; That C, N, Mg, K, Ca, Cu, Mn, Fe and Zn content in most organs of Chinese fir seedling showed that the higher concentration was, the less content was; but Al content show that the higher concentration was, the more content was.(3) Root extract of Chinese fir by supercritical fluid extract technology 1 (only CO₂ as entrainer, the following is the same) and fluid 2 (after adding the entrainer ethanol, the following is the same) at different parameter inhibited the germination summit and each germination index at different level. The bioassay revealed that except parameter 1, 7 and 8, the extract of supercritical fluid one had inhibitory effects on most germination...