Abstract: 【Objective】 To clarify the main factors affecting the occurrence and identify the pathogen species of seedling disease of the direct seeding cotton without film mulching after harvested rape in the hope of laying a foundationfor the targeted prevention and control of seedling disease in this model.【Methods】 The influence of meteorological conditions on seedling disease was analyzed by means of investigating of meteorological data and the regularity of dead seedlings. The pathogenic bacteria were isolated by conventional tissue separation method, and their classification was determined by morphological and molecular biological identification.【Results】 In the years of 2016 and 2019, the period from the first rainfall to the emergence of dead seedlings after direct seeding was 8 and 9 d, and the duration was 17 and 16 d respectively. There was a heavy rainfall in the previous week before the peak period in both two years. A total of 53 strains were obtained through pathogen isolation. The isolated strains were classified into Fusarium, Alternaria, Aspergillus, Rhizoctonia and Epicoccum, accounting for 39.6%, 32.1%, 20.7%, 5.7% and 1.9%, respectively. There were 21 strains,17 strains,11 strains,3 strains and 1strain which belonged to Fusarium,Alternaria,Aspergillus,Rhizoctonia and Epicoccum,respectively.【Conclusion】 Amount of rainfall is one of the most important factors affecting seedling disease of the direct-seeding cotton without film mulching after harvested rape. The disease mainly occurred about one week after the first rainfall after sowing, the peak period was one week after heavy rainfall, and the prevention measures of seedling diseases should be taken particularly at this stage. The isolated pathogens strains were mainly Fusarium, Alternaria and Aspergillus, followed by Rhizoctonia and Epicoccum.

Key words: direct seeding without film mulching; seedling diseases; rainfall; pathogen; identification

摘要： 【目的】 研究油后免膜直播棉苗期病害发生的主要影响因子及鉴定引起苗期病害发生的病原种类,为该模式下苗期病害的针对性防控奠定基础。【方法】 结合气象数据及死苗发生规律,调查分析气象条件对苗期病害的影响;采用常规组织分离法分离病原菌,利用形态学鉴定和分子生物学鉴定明确其分类地位 。【结果】 2016和2019年直播后首次降雨到开始出现死苗的时间分别为8和9 d,持续时间17和16 d,2年2次发病高峰期的前1周均出现1次强降雨;分离病原共获得53个菌株,其中,T9、M1、M52、M53等21个菌株属于镰刀菌属,占分离到菌株总数的39.6%,链格孢属菌株17株,包括T5、M9等,占总数的32.1%,曲霉属11株,如M17等,占总数的20.7%,丝核菌属如M1-15和附球菌属分别为3和1株,占分离菌株的5.7%和1.9%。【结论】 降水量为影响油后免膜直播模式下棉花苗期病害发生的最重要因子之一,病害主要在距播种后第1次降雨1周左右的时间开始发生,且强降雨后1周为发病高峰期,做好苗期病害防控。分离到的病原菌中以镰刀菌属、链格孢属和曲霉属为主,其次为丝核菌属和附球菌属。

关键词: 油后免膜直播, 苗期病害, 降雨量, 病原, 鉴定