Studies On The Allelopathic Effects On Different Chinese Fir Clones Under Phenolic Acids Stress

Plant allelopathy is refered to any beneficial or harmful effect by one plant releasing specific secondary matters on other plants neighborhood.,widely exists in many species in nature. Allelopathy of Chinese fir(Cunninghamia lamcealata(lamb.)Hook) has been confirmed by the domestic scholars. The accumulation of autoxins can result in land degradation and productivity decline in Chinese fir plantations. At present, it has been identified that gallic acid, salicylic acid and cinnamic acid and many other substances were the Chinese fir allelochemicals.In this study, by adding the exogenous gallic acid, salicylic acid and cinnamic acid into MS culture medium in regressive rotation design, the stress experiment have been carried out to research the different allelopathic effects of three phenolic acids stress on some physiological processes. A series of the quadratic equations of three factors on some physiological processes were seated up by measuring the relative conductivity, MDA content, SOD activity and Chlorophyll fluorescence parameters Fv/Fo and Fv/Fm of the two kinds of Chinese fir clones (including tolerant type and sensitive type) leaves at different stress periods (prophase0-15 days, metaphase 16-30 days, anaphase 31-45 days), calculate the allelopathic index and with the variance analysis of structural matrix of the three factors and the correlation coefficient, analysis the interactive effect of three phenolic acids. The main results were as follows:(1)The allelopathic effect of relative conductivity for Chinese fir's clones under the stress of phenolic acids, in the prophase of stress, the allelopathic effect between the two clones didn't show much difference, when the concentrations of these three phenolic acids were low, the allelopathic effect appeared to be inhibited, and under the same conditions the inhibited effect tend to be weaker on FS23; when the concentrations of these three phenolic acids were high, the allelopathic effect appeared to be stimulated effect and the stimulated effects were much more stronger on FS23 than on FS11, and the stimulated effects of these two clones became intensified as the stress time prolonging, in the anaphase the stimulated effects increased significant, and the stimulated effects of the FS23 was much stronger than FS11.(2) The allelopathic effect on the MDA content of Chinese fir's clones, at the initial period of the stress, as the concentration of the stress changed, the allelopathic effects of the two clones tend to be the same, but in the same conditions the inhibited effects of the FS11 was stronger than that of FS23; in the intermediate stage the allelopathic effect of FS11 didn't change much, only show a little increased in allelopathic effect index, whereas the allelopathic effect of FS23 in each disposes shown a stimulated effect and what's more it shown a great increased in allelopathic effect index; in the anaphase both of the Chinese fir's clones shown an stimulated effects, however, the allelopathic effect index of the FS11 was much weaker than that of FS23.(3) The allelopathic effect on the SOD activity, in the prophase, the SOD activity of each disposes shown an stimulated effect and under the same disposes the stimulated effect on FS11 was much stronger than that on FS23; in the metaphase, the SOD activity stimulated effect declined significant and as the concentration of the phenolic increased the allelopathic effect was changed into inhibited effect from stimulated effect, and the decline range of the stimulated effect on FS11 was much smaller than that on FS23; in the anaphase both the allelopathic effect on the Chinese fir's clones shown inhibited effect, and the inhibited effect was weaker on FS11 than on FS23 under the same dispose.(4) In the prophase of stress, the Fv/Fo and Fv/Fm of the two clones leaves have the same allelopathic effects, appeared to be stimulated effect at low concentration and inhibited effect at high concentration; in the metaphase, the stimulated effect of FS11 was decreased, it shown inhibited effect at low concentration of phenolic acids, on the contrary, when the concentration of phenolic acids were increased, allelopathic effect tend to be stimulated effect, however, each disposes of the FS23 shown inhibited effect no matter what the concentration of phenolic acids is; in the anaphase, both of the allelopathic effect in two clones shown inhibited effect, and FS11 was lower than FS23; in the whole stress process, Fv/Fo shown more sensitivity than Fv/Fm under the stress of phenolic acids.(5)The three phenolic acids have the same influence on the two clones, during the stress time, it shown that three phenolic acids appear to have limiting effect at low concentration and increasing effect at high concentration for both of relative conductivity, and content of MDA, and it shown that it have a increasing effect at low concentration and have a limiting effect at high concentration for SOD activity and Chlorophyll Fluorescence, however, as the stress time lasted, allelopathic effect will changed in certain extent. What's more there have interaction among these phenolic acids, the interaction trend to be the same phenomena as the SOD activity and Chlorophyll Fluorescence. But in the different periods of stress time, different clones, different biochemical and physiological process, the critical concentration of the change between limiting and increasing have some differences(5)The three phenolic acids have the same influence on the two clones, At the initial period, it shown that three phenolic acids appear to be limiting effect at low concentration and stimulated effect at high concentration for both of relative conductivity, and content of MDA, and it shown that it performed a stimulated effect at low concentration and a inhibited effect at high concentration for SOD activity and Chlorophyll Fluorescence, however, as the stress time lasted, allelopathic effects will changed in certain extent. In addition, the phenolic acids have interactions effects with each other, and the interaction effect is closely related to the concentration level of phenolic acids,it turn out to be promoted under low concentration and inhibited adverselyBut in the different periods of stress time, different clones, different biochemical and physiological process, the critical concentration of the change between inhibited effect and stimulated effect have some differences.