Identification Of The Pathogens Of Late Blight On Tomato And Screening Of Resistant Germplasm

Tomato late bilght which caused by Phtophthora infestans (Mont.) De Bary. is a fungal disease and often happens not only in fields but also in protected fields. Recent years, the disease expanded to almost all of the world. With its increasing seriousness we must find a feasible and effective method to solve this problem. Disease-resistant breeding is the most effective and direct method to deal with the disease up to now. The study first began with the isolation and identification of the pathogen and then the biological characteristics of the pathogen were studied; then found a convenient method of screening tomato seedlings resistant to Phtophthora infestans (Mont.) De Bary. and identified the tomato late bilght physiologic race in LIAO NING, JI LIN and HEI LONGJIANG province. With this method almost 60 tomato varieties provided by tomato breeding laboratory of Horticulture Institute in North East Agriculture University were appraised in resistance to late bilght pathogen, and lays a foundation for tomato late blight breeding. The results were as follows:First, after isolation , identification and purification of tomato late blight pathogens from different regions, we confirm that all pathogens we got belong to Phtophthora infestans (Mont.) De Bary. and the cultural characteristics and virulence of different isolates have some difference to a certain extent. rye culture medium, oats culture medium; the most suiTab. culture medium for the spore growth is rye culture medium; the most suitable temperature for the growth of mycelium and spore is 20℃; the most suiTab. pH for the growth of pathogen 6. 5 and 7. 0 is the most suiTab. PH for spore growth; light can inhibit the growth of pathogen and spore;the most suiTab. sugar for spore is sucrose and the most sutiTab. is 15g/1000ml; When mycelium pe rmeated the culture dish, put them to incubator with 10℃ can increase spore growth.Second, the results shows the thermal death point of tomato late blight pathogen is 45±1℃; the pathogen have vitality to some extent after 6 month in refrigerator with 4℃, and can grow slowly;tomato late blight sporangium begin release zoospore after 10 min at room temperature, amount of zoospore get 30-50% after 3 hours and after 8 hours all zoospore released (observed with counting chamber ); Put forward the purification method of mycelium when polluted for the first time.Third,Several methods of identification of resistant to tomato late bilght at...