Abstract: 【Objective】To determine the conditions regulating the sclerotia germination types of Sclerotinia sclerotiorum in sunflower,aiming to effectively reduce the damage of Sclerotinia disease to sunflower.【Methods】Sclerotia of S. sclerotiorum in sunflower were used as the experimental material,and the field conditions were simulated to analyze the differences in the numbers of sclerotia mycelium germination and apothecium formation under treatments including environmental factors （light,soil relative water content,temperature,humidity,soil coverage,germination times,physical damage） and intrinsic factors （sclerotia age）,and the antioxidant enzyme activities of strains with different sclerotia ages were determined.【Results】From the perspective of environmental factors,light favored apothecium formation,a soil relative water content of 25%-35% favored mycelium production,while 75%-95% favored apothecium formation;temperatures of 15 ℃ and 15-20 ℃ favored apothecium formation;sclerotia with no soil coverage were more likely to germinate to produce mycelia and form apothecia; sclerotia subjected to low temperature treatment for 60 d did not produce mycelia,but the sclerotia number forming apothecia （40） was significantly higher than that of other treatments（P<0.05）;the sclerotia number forming apothecia after one germination was significantly higher than that after two and three germinations（P<0.05）,while the sclerotia number producing mycelia was significantly lower than that after two and three germinations（P<0.05）;the sclerotia number producing mycelia from physically freeze-injured,mechanically damaged and incompletely colored sclerotia was significantly higher than that of CK（P<0.05）,while the sclerotia number forming apothecia was significantly lower than that of CK（P<0.05）. From the perspective of intrinsic factors of sclerotia,sclerotia of 1 d age germinated earliest to produce mycelia,with the sclerotia proportion producing mycelia reaching 100%;among sclerotia of 30 d age,the sclerotia number forming apothecia was significantly higher than that of other treatments（P<0.05）;the activities of superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） decreased with the increase of sclerotial age and gradually tended to be stable.【Conclusion】The sclerotia germination types of S. sclerotiorum in sunflower are jointly regulated by environmental factors and intrinsic factors of sclerotia. Soil relative water content,low temperature treatment time,germination times and sclerotia age are the key factors regulating sclerotia germination types.

Key words: Sunflower, Sclerotinia sclerotiorum, Environmental factors, Intrinsic factors, Mycelia, Apothecia