Effects Of Biogenic Substances On The Promotion, Induced Resistance And Disease Prevention Of Several Vegetables

With the improvement of living standards, there is a growing demand for the anti-seasonal vegetables. Development of Facility Agriculture has not only promoted the annual production of vegetables, but also caused the frequent occurrence of pests and diseases, complications as well as chemical abuse in recent years. Furthermore, excessive use of chemical pesticides can not only cause "3R" problems, but also damage the ecological balance and endanger human health. Therefore, it is important to develop a safe and effective pesticides to control the diseases and insect pests. Biogenic materials, coming from living organisms and safe for environment and human, can be used as fungicide to control plant disease and plant growth regulators to promote plant growth. Thus, they have been widely applied in practice recently. To investigate the effects of the three kinds of biogenic materials--S-auxin, organic fertilizer and oligosaccharides on vegetable growth, induced resistance and disease prevention, seeds of tomato, lettuce and cucumber were treated with five different concentrations of three kinds of biogenic materials and then measured their germination rate, radicle and plumule length after presoaking and germination. Our results showed that germination of seeds as well as elongation of radicle and germ were inhibited under high concentration of S-auxin (diluted <2500 times). Treatments with different dilutions of organic fertilizer and oligosaccharides had no significant effect on germination of vegetable seeds, but could promote elongation of radicle and germ under the concentration of diluted with 2000～4000 times and 800～3200 times respectively. Among these treatments, organic fertilizer diluted by 4000 times had better effect on elongation of tomato radicle and the rate of increase was 160%. Continuous spraying 2 times with the recommended concentration, three kinds of biogenic materials all could promote the growth of plants. In detail, organic fertilizer can increase 321% of the dry weight and 38% of the height tomato, respectively; oligosaccharides can increase 143% of the fresh weight of tomato.The determination of defense enzyme activity showed that three biogenic materials could increase the activities of phenylalanine ammonia (PAL), peroxidase (POD) and polyphenol oxidase (PPO) in plants, and all of these enzymes activity reached the maximum in 24～72 h after the treatment, but they had little effect on superoxide dismutase (SOD). In addition, the determination of related resistance substances indicated that the three biogenic materials could increase the content of soluble sugar and lignin in the plants after treatment of 3-7d, but significantly decreased malondialdehyde (MDA) content and no apparent changes of soluble protein contents.Three biogenic materials could control Tomato Gray Mold, Lettuce Sclerotinia and Cucumber Powdery Mildew to some extent, and thecontrol effect of organic fertilizer on cucumber powdery mildew was 68%. When the organic fertilizer was used with the filtrate of the actinomycetes combinedly, the control effect on Cucumber Powdery Mildew increased to 81%. Real-time PCR results suggested that the expression levels of PAL gene, β-1,3-glucanase gene and PR gene were significantly up-regulated in vegetables, especially after treatment of organic fertilizer and the expression level of PAL gene in tomato plants increased more than 3 times.In summary, several kinds of biogenic materials can effectively promote the growth and induce the resistance to pathogenic germs of vegetables. Owing to the biogenic material itself is non-toxic and environmental security, it is the ideal material to use with other pesticides on controlling vegetable diseases.