Studies On The Mechanism And Control Approaches Of Replant Obstacle In Grape

The grape replant problem is expressed as stunted growth, low productivity and a decline in tree vigor leading to shortened economic life. At present, the problem is common in all grape growing regions and has seriously restricted the development of grape industry. In order to study the reason of grape replanting, using rhizosphere soil, non-rhizosphere soil and fallow soil of replanted vineyard and new-planted vineyard which had been planted grape for 30 years and 3 years respectively as research object, and tissue culture seedling of Red Globe (V. vinifera L. cv), tissue culture seedling of'Shanhe No.2'grape and pot seedling of Beta (V riparia×V. labrusca cv.) as experimental material, changes of soil microbe and physic-chemical properties were analyzed, and allelopathy of root exudates, root aqueous extracts and root decomposing products were studied, and major allelochemicals were determined, and its effect on grape growth and rhizosphere microenvironment were further analyzed, at the same time, the effect of adding organic materials and inocula into replanting soil on alleviating grape replant obstacle were studied. The major results were as follow:1. Biological factor played a causal role in the development of grape replant obstacle. Based on pot experiment, the results indicated that root activity, leaves chlorophyll content and net photosynthetic rate which plant grew in root zone soils of replanted vineyard decreased compared to plants which grew in new-planted vineyard, and plants growth was weak. After sterilization of replanting soil, SOD activity of grape leaves increased, while MDA content decresed, and root activity enhanced first and then declined, and plant height, stem diameter, fresh weight of shoot, fresh weight of root increased. Comparing with grape growing on replanting soil, the content of soluble sugar and amino acid of root exudate for grape growing on sterilized replanting soil deceased by 72.60% and 91.10%, and amino acid composition of root exudation also changed.2. Soil microbial number and population structure changed after grape replanting. The numbers and proportions of bacteria and actinomycetes in rhizosphere soil of replanted vineyard decreased, and the number and proportion of fungi increased. Bacterial and fungal diversity in replanted vineyard was higher than that in new-planted vineyard, and the diversity in rhizosphere soil was greater than that in non-rhizosphere soil. Compared with the new-planted vineyard, grape replanting caused a great change in microbial population of rhizosphere soil. The content of Flavobacterium sp. (DQ339585) and Bacillus sp. (AY039821) decreased, while Pedobacter sp. (AJ871084) increased in bacteria. Omphalina farinolens (EF413029) appeared, and the content of Pestalotiopsis sp. (DQ657877, DQ657875, DQ657871), Phacidium lacerum (DQ470976) and Lecythophora decumbens (AF353597) decreased, while Pilidium acerinum voucher (AY48709) increased in fungi. Among them, Bacillus sp., Flavobacterium sp. and Pestalotiopsis sp. in rhizosphere soil of replanted vineyard had antagonism to pathogen, and the decrease of relative amount reduced resistance against pathogen. Increasing of Pilidium acerinum voucher might relate to severe disease after grape replanting.3. Soil physical properties were not deteriorated after grape replanting, while nutrient ratio was inbalance. Soil bulk density, acidity and conductivity decreased after grape replant. Soil organic matter and macroelements (N, P, K and available Ca, Mg) increased along with the prolonging of grape planting peroid, available Fe, Mn were deficit in replanted vineyard soils, while available Cu, Zn increased. Zn/Mn, Zn/Fe, N/Fe, N/Mn, P/Fe, P/Mn, Ca/Fe and Ca/Mn were imbalance in the root zone, and among them, Zn/Mn, Zn/Fe were most serious imbalance.4. Grape root exudates, aqueous extracts, root decomposing products had significant autotoxicity, and in which five allelochemicals were identified. Using the testing methods of tissue culture seedling, the results showed there were significant autotoxicity in grape root exudates, aqueous extracts of grape root, root decomposing products, and in which 5 phenolic acids (p-hydroxybenzoic acid, salicylic acid, coumaric acid, phenylpropionic acid and benzoic acid) were isolation and identification, and they were important allelochemicals. 5 acids (phthalic acid, palmitic acid, citric acid, gallic acid and aconitic acid) and 2 alcohols (1-heneicosanol andβ- sitosterol) was infered in root exudates and root decomposing products. Among them, low-concentration phthalic acid, palmitic acid, citric acid, and gallic acid promoted plant growth, and high concentration of which inhibited plant growth significantly. There were no regular change on grape growth under 1-heneicosanol treatment, and low-concentrationβ- sitosterol inhibited plant growth, while high concentration of which promoted plant growth significantly.5. Root exudates and root decomposing products changed microbial population structure and available N, P, K content of rhizosphere soil. There were no significant difference in available N content of rhizosphere soil between root exduate treatments and control. Low concentration (E100 and E200) root exudates made available P, available K contents of rhizosphere soil increased. Available P, K content of rhizosphere soil decreased under the treatment of high-concentration (E300) root exudates, which made rhizosphere soil transform from bacterial forms to fungial forms. The treatments of root decomposing products increased available N, available P and available K content of rhizosphere soil, decreased fungal diversity, made Trichoderma disappeared, Pythium, Thielaviopsis, Stilbellales appeared.6. Phenylpropionic acid and salicylic acid inhibited plant growth through disturbing membrane and related physiological process. Based on pot experiment, the results indicated that phenylpropionic acid and salicylic acid of different concentration (0.1mmol·L-1, 1mmol·L-1, 10mmol·L-1) enhanced cell membrane permeability, decreased SOD activity and root activity, affected photosynthesis and dry matter accumulation of grape leaves. So, they decreased significantly plant height, stem diameter, fresh weight of shoot and root with the rise of concentration, and resulted in growth vigor weak.7. Rice straw and corn straw improved soil physical properties, activated soil nutrients and ameliorate microenviroment of rhizosphere soil, which promoted grape growth. The measures of adding different proportion rice straw and corn straw into replanted soil decreased soil bulk density, increased soil porosity, organic matter content, available P, available K, and seedlings had strong growth vigor (except for the treatment of 0.5% rice straw adding into replanting soil). The proportion of microflora changed after treatments, and the ratio of bacteria increased. Moreover, soil phosphatase activity increased with decomposition time prolonging of organic materials, and soil catalase activity increased after adding corn straw into replanting soil, while rice straw treatment did not increased soil catalase activity.8. AMF (arbuscular mycorrhizal fungi) promoted plant growth, and changed root exudation characteristics. AMF (Glomus versiforme G.V, Glomus mosseae G.M and Glomus etunicatum G.E) promoted significantly plant growth, and SOD activity increased, MDA content decresed, root activity increased, among them, GV and G.M treatments were better. AMF (Arbuscular Mycorrhizal Fungi) also affected grape root exudation characteristics, and substance species and relative contents of grape root exudates were changed greatly in different treatment. G.V treatment had more substances and specific component nerolidol.9. Lilac paecilomyces, biocide and EB were important control approaches of grape replanting. After inoculating lilac paecilomyces, biocide and EB into replanting soil, SOD activity of grape leaves and root activity increased, and MDA content of leaves reduced. Soluble sugar content, starch content and protein content of grape leaves increased after inocula treatment, and root activity raised. Lilac paecilomyces treatment in which DZ2 (30 g lilac paecilomyces of per groove) was best, and biocide treatment in which MM2 (500 g biocide per groove) was best, while EB treatment in which EB1(20 g EB per groove) was best. Comprehensive analysis result showed that the effect of biocide and EB on grape growth better than lilac paecilomyces.