【摘要】 华北地区所发生的小麦丛矮病证明是由北方禾谷花叶病毒(NCMV)所致,并由灰飞虱所传染,文中记述了在我国发生的历史及分布的情况。发病小麦在田间的症状可以分为四个类型:1、植株正常,叶上有退绿或黄色线条,2、植棒正常或稍矮,叶脉间有严重退绿或变黄,根部发育稍差,3、植株中等矮化,有宽的退绿条纹,叶脉亦变色,分蘖增多,4、植株严重矮化,分蘖异常增多,根系发育恶劣。轻症植株常发展成为重症株。重症植株不能越冬。有些轻症植株后期有隐症现象。根据病情轻重,在田间调查中划分0、Ⅰ、Ⅱ、Ⅲ四级,逐级称取千粒重,结果Ⅰ级病株的千粒重损失为52.6%,Ⅱ级为66.7%,Ⅲ级为93.23%。更多还原

【Abstract】 The rosette disease of wheat in North China has been demonstrated to bea virus disease transmitted by the planthopper Laodelphax strietellus.Theisdisease is similar to the northern cereal mosaic in many respects.It wasfirst noted in Hopei province in 1949、but was then rather sporadic.The firstepiphytotic of this disease occurred in 1965 in Shangtung province and hen-ceforth it had been frequently reported from several other districts in Nor-th and Norhwest China.The symptoms of the diseased wheat plants are ten-tatively grouped into four types:1.plants are normal in height,but with yellow or chlorotic streaks onleaves.2.plants are normal in height or show a little dwarfing but with severechlorotic or yellow stripes between green veins.Roots are more or less under-developed.3.plants are moderately dwarfed,with broader chlorotic stripes in whichthe veins are also chlorotic.Tillers may or may not increase.4.plants are severely dwarfed and produce abundant tillers causing arosette feature and the root development is very poor.The milder symptoms us-ually develop into severe ones,but either in greenhouses or in fields sympto-ms may disappear so that the infected plants look recovered.The plants with seve-re symptoms usually die before overwintering.For the convenience of field survey,the degrees of infection in time ofheading are grouped inso four classes.Class 0,healthy or normal plantsClass Ⅰ,plants are dwarfed and reduced to more than 2/3 of its normal hei-ght,while tillers may or may not increase,Class Ⅱ,plants are reduced to1/2 of its normal height and tillers are abundant.They are capable of headingbut heads are fewer and smaller and sometimes empty.Class Ⅲ,plants areseverely dwarfed with profuse tillers.Usually they are-incapable of headingand die before overwintering.The grains produced by the-infected wheatplants in the four classes are weighed for their 1,000 grains weight.The loss-es of 1,000 grains weight of Class Ⅰ,Ⅱ and Ⅲ in comparison with thatof Class 0 are 52.6%,66.7% and 93.2% respectively.更多还原