Effects Of Four Plant Immunological Agents On The Resistance Of Tobacco To Diseases And Insect Pests

Tobacco is an important cash crop in China for its important role in agricultural,while chemical control remains the most common measure in tobacco pest prevention.The wrong use of pesticide would lead to several problems including pesticide residue,pollution and pesticide resistance.To solve these problems,we developed new measures in tobacco pest prevention by using oligosaccharide and protein plant immune agents.The indoor growth rate inhibition assay and indoor seedling pot culture identification assay were used to examine the inducing effects in Myzus persicae and tobacco brown spot disease and the enhancement effects in tobacco growth leaded by four plant immune agents.The field control effects of oligosaccharides and Altailing on tobacco diseases were determined.Our research would provide an effective way and theoretical basis for further research on new bio-agents against crop diseases and insect pests.The research results can list as follows:1.Effects of different plant immune agents on the growth of tobacco seedlings:The effects of chitosan oligosaccharide 1,chitosan oligosaccharide 2,pectin oligosaccharide and altailing on tobacco were determined by houseplant method.The results showed that different plant immune agent has a certain promoting effect on tobacco growth.Among them,0.050 mg/mL chitooligosaccharide 1 and 0.050 mg/mL pectin oligosaccharide have relatively good growth promoting effects on tobacco.2.Effects of Plant Immunity on the Changes of Chemical Components in Some Tobacco Seedlings:The content of soluble protein in tobacco leaves treated by four plant imnune agents was determined by UV absorption method.The results showed that the soluble protein content of tobacco leaves after treatment with 0.050 mg/mL chitosan 2,The highest is 0.122;1000 times Ataying has the lowest content after treatment.The chlorophyll content of tobacco leaves treated with four plant immune agents was detected by spectrophotometer.The results showed that the contents of chlorophyll a,chlorophyll b,carotenoids and chioroplast pigments in tobacco increased.The eontent of chlorophyll a and carotenoids was the highest after treatnent with 0.050mg/mL pectin oligosaccharide,and the content of chitosan oligosaccharide 2 was the lowest after treatment with 0.050 mg/mL.The content of chlorophyll b was the lowest after treatment with arhatin3.Induction of Tobacco Resistance to Myzus persicae by Plant Iumunity:The indoor planting method was used to treat tobacco plants with foliar application of 0.050 mg/mL oligosaccharide and 1000 times Altailing solution.(1)induced tobacco resistance to aphid,After spraying the plant immunization agent,the rate of aphid worms decreased continuously,and the aphids could be controlled.The effect was not significant.After the second spraying of the plant immune agent,the rate of mites decreased to a maximum of 24.97%.The third spraying was applied.After that,the rate of decrease in the larvae is reduced.(2)The selectivity of aphids was induced,and the selectivity of aphids to tobacco was reduced after the tobacco plants were treated with different plant immunity agents.4.Inhibition effect of different plant immunity agents on tobacco brown spot disease:setting chitosan oligosaccharide 1,chitooligosaccharide 2 and pectin oligosaccharide to 0.050 mg/mL and 0.075 mg/mL respectively,The method which uses indoor growth rate to inhibit fungi was applied to determine the inhibitory effect of plant immune agents on the pathogenic fungi of brown spot disease.The results showed that the three plant immunity agents had certain inhibitory effects on the pathogenic fungi of brown spot disease.When the concentration was 0.050 mg/mL,the chitosan oligosaccharide 1 solution had the best inhibitory effect on pathogenic fungi.When the concentration was 0.075 mg/mL,the pectin oligosaccharide solution had the best inhibitory effect on pathogenic fungi.The 1000 times Ataying solution also has a certain inhibitory effect on the pathogenic fungi,and the inhibitory effect is lower than that of the oligosaccharide solution..5.Field efficacy test of different plant immunity agents against tobacco virus disease:The results showed that by applying plant immunization agents in the late stage of tobacco seedlings and in the early field,the occurrence of tobacco virus disease can be controlled to some extent,Effectively mitigates the risk of tobacco virus disease in the field...