Establishment Of Sunflower Broomrape Parastism System Under Lab Condition And Identification The Pathogen Caused Sunflower Broomrape Necrotic Spot By Koch Postulate

Orobanche cumana Wallr.is a kind of parasitic seed plant of sunflower,and it caused dramatically yield loss annually.In this study,we set up seeds germination and parastic system under lab conditions,and identify the resistance level of sunflower varieties using this system.Meanwhile,the pathogen caused broomrape necrotic spot was identified by Koch postulation;the results were listed as follows:1.We collected the different biotypes of sunflower broomrape,which showed the difference on the flower color and inflorescence shape and number;and the branch broomrape of sunflower was also found in Inner Mongolia region.2.The seeds shape and size of diff'erent species within same Orobanche genus is variable.Whereas,it is much more similar on the seed shape and size among the different race type of Orobanche cumana.3.We also studied the occurrence of sunflower broomrape under laboratory conditions,the results indicated that different soil pH value.moisture content,soil type do have effects on the germimation of sunflower broomrape.The10%-20%soil moisture in alkaline.sandy loam is easy for the parasitism on sunflower roots.4.By comparing the three kinds of Orobanche seeds germination and parasitic system,the filter paper in petri dish is the fast and efficient germination system under lab condition.5.Via Koch postulation,P.cucumerina was isolated and identified as causal agent caused sunflower broomrape necrotic spot.Pathogenicity differentiation results indicated that that P.cucumerina isolated from sunflower broomrape showed the different pathogenicity on different hosts such as tomato,sunflower and sunflower broomrape.