Research Of Effects Of Phenolics On Malus Hupehensis Rehd. Seedlings

Replant disease is one of most difficult problems in the process of renew of old orchard. Autotoxicity of phenolics is one of the most important factors contributed toward the occurrence of crop replant disorder. So, studying on autotoxicity about phenolic acids has a great significance to theories and production.The annual apple seedlings of Malus hupehensis Rehd. was used as materials to study the mechanism of detriment made by exudation in replant disease, when benzoic and cinnamic acids of different concentration and the contour mixture of the two were added. The main results were as follows:(1) The effects of phenolic acid on photosynthesis of Malus hupehensis Rehd. seedlings were different amind different concentrations. Three phenolics about 5 mg·kg-1soil on Pn, contents of chlorophylla, chlorophyllb and carotenoid, Fv/Fm,Fv/Fo,Fv'/Fm'and (Fm'-Fs)/Fm'were higher than control, improved in the early period and declined following the time,but qN was lower than control; The data of above index about 25 mg·kg-1 and 125 mg·kg-1 phenolics were opposite to 125 mg·kg-1 concentration's. All data of different phenolics and concentration on Malus hupehensis Rehd. seedlings were approach to control.(2) 5 mg·kg-1(soil) phenolic acid increased the activity of SOD, POD, and CAT, while it decreased the contents of O2—. and MDA. The contents of–SH were highter than the control, respectively. In addition, there were no significant differences between 5 mg·kg-1(soil) and CK in above data. At 25 mg·kg-1(soil) and 125 mg·kg-1(soil), activities of SOD and POD increased firstly, then decreased. CAT activity decreased firstly and increased over the time, but lower than CK. O2—. and MDA contents were improved in the early period and declined following the time. -SH content declined during the treatment time.(3) Phenolic acid significantly decreased respiration intensity of root of Malus hupehensis Rehd. , and decline rates with the time and concentration's increase. Respiration intensity of A1, A2 and A3 on 11th were 89.8%, 59.2% and 39.2% in control, respectively.(4) Three respiration pathways (PPP, EMP, TCA) have similar tendency of phenolic acid on Malus hupehensis Rehd. seedlings, and the tendency decreased all the way and there is not tendency to control.