2012•Northern HorticultureRequires access
Effect of Temperature and Moisture to Sporangium Germination and Formation of Cucumber Downy Mildew
Niu Zhenfu
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Abstract
With ‘3 rd Lu cucumber’ as test materials,the effect of temperature and moisture to sporangium germination and formation of cucumber downy mildew were studied.The results showed that temperature and moisture showed significant affection on germination and formation of sporangia and the role of moisture was more important than temperature.The sporangia germinated at the temperature ranged from 10to 30℃,with optimum at 20℃.The germination of sporangia required free water and the sporangia could not germination without free water,even though at saturated humidity.Lesions of downy mildew formed sporangia at the temperature ranged from 10 to 35℃.The quantity of sporangia formed at different temperature was significantly different and more sporangia were formed at 15～20℃.When leaves were wetted,the lesions formed plenty sporangia.The quantity of sporangia formed by wet lesions was significantly more than the leaves in saturated humidity.Lesions did not form any sporangia in dry condition(RH=45%).