Effect Of Pesticides Against Tobacco Weather Fleck And Mechanism Of Tobacco's Physiological Response

Tobacco weather fleck is a non-infectivity plant disease because of ozone injury.Along with the development of industrialization and the increasing of the atmospheric waste gas,Tobacco weather fleck occured widely day by day it caused more losses in various tobacco growing areas. Because the perfect pesticides against tobacco weather fleck have not been discovered while the research work of pesticides development lagged relatively at present,the question of tobacco weather fleck's control has been difficult to solve in tobacco production process.The research based on pesticides different action mode,taking Brassinolide,Tianda-2116 and Sodium nitrophenolate three plant growth regulators and Thiophanate-methyl,Mancozeb and Carbendazim three fungicides as the object of investigation,through the field test and the laboratory test,carring on pesticides selection,the allocated proportion optimization and the effect evaluation,was for the purpose of selecting the effective prevention tobacco weather fleck to the pesticides mix matches, and investigated the physiological change of the tobacco after pesticides were sprayed,the mechanism of tobacco's physiology response were investigated,obtained the control tobacco weather fleck ideal pesticides,confirmed the function mechanism of the related pesticides,to control tobacco weather fleck to lay the solid foundation.The results obtained findings were as follows:1,The effective pesticides against tobacco weather fleck was selected.Useing the field plot experiment to study three plant growth regulators as Brassinolide,Tianda-2116,Sodium nitrophenolate and three fungicides like Thiophanate-methyl,Mancozeb,Carbendazim as well as their mixtures against tobacco weather fleck.The test results indicated that 0.01%Brassinolide EC(2000 times),Tianda-2116 AS(600 times),70%Thiophanate-methyl WP(1000 times),70% Mancozeb WP(500 times) and 50%Carbendazim WP(500 times) were effective to control the tobacco weather fleck,each of these pesticides' relative control effect was approximately 40%, between them difference were not significant(P＞0.05),but effect of different Sodium nitrophenolate(30000 times) against tobacco weather fleck was bad;The effect of different plant growth regulator and fungicides mixtures against tobacco weather fleck had significant difference. Thiophanate-methyl and Brassinolide mix match(m:m=2:1),Thiophanate-methyl and Tianda-2116 mix match(m:m=1:1),the relative control effect were over 70%,the effect of Mancozeb and Tianda-2116 mixes match(m:m=1:1) against tobacco weather fleck was 67%,but effect of three fungicides and the Sodium nitrophenolate mixtures against tobacco weather fleck were poor,even were lower than the effect of single funficide.Through the agriculture characters investigation,mix matches pesticides were sprayed to enhance the tobacco leaf's extent the output and the quality. The overall evaluation on control effect and agriculture characters,the effect of Thiophanate-methyl and Brassinolide mix matches was the best,surperior to other mix matches and one pesticide single.2,The greenhouse experiment of tobacco weather fleck induction and the mixture pesticides of the best proportion selection were achieved.Through the treatment of the ozone high concentration and low temperature,the weather fleck was induced in the greenhouse.The results indicated that the similar symptom to weather fleck was not found in the only low temperature(10℃) treatment,or the ozone(0.7mg/L) and so on sole factor stress,but the low temperature(10℃) and ozone (0.7mg/L) treated together after 24h,the white hollow necrosis spot was presented in the tobacco leaf blade,this symptom was similar to the field weather fleck symptom,owing to the ozone injury was determined.Along with the time expand the spot quantity was not found increased;Through investigating the tobacco weather fleck's occurrence after the pesticides prevention to research the pesticides control action.It was indicated that when the concentration of Thiophanate-methyl and Brassinolide mix matches was(700+0.5) mg/L,the control effect was best,it was up to 62.17%.3,The mechanism of tobacco's physiological response was made clear after mixture pesticides treatment.After Thiophanate-methyl and Brassinolide mix match(700+0.5)mg/L treated,the tobacco physiological change was determined after 24h in low temperature and O₃ stress.The results indicated that mix matches the pesticides could maintain stable relative conductivity.The content of chlorophyll-a decreased,but chlorophyll-b and total chlorophyll quantity did not change significantly(P＞0.05),but with comparison treatment difference was significant(P＜0.05), simultaneously the activities of surperoxide dismutase(SOD),the catalase(CAT),the ascorbate peroxidase(APX) enhanced very significant(P＜0.01),higher than contradistinguish 232.8%, 92.5%,51.1%respectively,but the peroxidase(POD) activity was not significant difference (P＞0.05).The effective pesticides against tobacco weather fleck were confirmed in this research.The mechanism of Thiophanate-methyl and Brassinolide mix matches was investigated,which had the vital guiding significance in preventing and controlling tobacco weather fleck.