历史查询   



 没有找到相关例句 
 The common root rot of wheat caused by Helminthosporium sorokinianum Sacc. et Sorok. (Cochliobolus sativus (Ito et Kurib. ) Drechs. et Dast.) has become one of the important diseases in South China in recent years.The present investigation, carried out in 1980 and 1981 in Guangdong Province,proved that the conidia of the causal fungus remained viable for more than 281 days in dry soil and less than 80 days in watersoaked soil. The soil in the regions where the main cropping system consisted of "wheatricerice"... The common root rot of wheat caused by Helminthosporium sorokinianum Sacc. et Sorok. (Cochliobolus sativus (Ito et Kurib. ) Drechs. et Dast.) has become one of the important diseases in South China in recent years.The present investigation, carried out in 1980 and 1981 in Guangdong Province,proved that the conidia of the causal fungus remained viable for more than 281 days in dry soil and less than 80 days in watersoaked soil. The soil in the regions where the main cropping system consisted of "wheatricerice" were not infested. Among the 30 species of plants, including crops and weeds, inoculated in the greenhouse, five kinds of crops and eleven species of weeds showed certain degrees of susceptibility,but these susceptible hosts had not been found in the fields. The infected seeds were found to be the main source of primary inoculum.By a comparison of five diffevent metnods of coumting the conidia in the soil, a method modified from Chinn's "FlotationViability Count Metnod" was recommended.  小麦根腐病是广东小麦重要病害之一。病原菌在干旱土壤中可存活281天以上,在淹水土壤中80天使死去,“麦→稻→稻”水旱轮作制的地区不存在土壤带菌问题。室外堆放的病秆所带分生孢子可存活281天以上,但菌丝体在220天以前死去,不能产孢传播。室内人工接种有6种作物和11种杂草感病,其中甘蔗、茭白、雀稗、纤毛鸭咀草和川谷为前人所未报道。但大田调查结果,除小麦外迄今未见有自然感病寄主。种子带菌很普遍,是广东小麦根腐病的主要初侵染源。 本试验对Ledingham和Chinn的土壤孢子数估算法作了改进,测定方法简单,较为准确,可供田间孢子量测定之用。  Under the Markovian extensionablc conditions of Doob [3],this paper discussed the problem of the Markovian extension transition matrix which can be represented in terms of parameters of the mixed spectra of a nonsingular stationary series.The main result is followingTheorem: Suppose that xt is a nonsigular[2] stationary scries, the spectrum of xt can be represented as(14) ,where satisfy the following conditions and the orders of zero points of φ(z)on {eiλk} are not greater than the orders of (?)(z) correspondingly,... Under the Markovian extensionablc conditions of Doob [3],this paper discussed the problem of the Markovian extension transition matrix which can be represented in terms of parameters of the mixed spectra of a nonsingular stationary series.The main result is followingTheorem: Suppose that xt is a nonsigular[2] stationary scries, the spectrum of xt can be represented as(14) ,where satisfy the following conditions and the orders of zero points of φ(z)on {eiλk} are not greater than the orders of (?)(z) correspondingly, then xt can be represented as a component of a N  variate Markov stationary scries y(n) which denoted by (15), where F is(16), {(?)i ,..., (?)}are coefficients of (17), {zi , j = 1,...,r + s}are all common roots of φ(z) and (?) (z) ; {βk}, C are defined in(18), (19), {ck, 0≤k≤p 1}can ae derived from (11)(13), {θ, 1,...,θp1}are coefficients of (20)and{εn(x)}in (15)are wold series [2]of xt.  本文的目的是讨论一般非奇异平穗序列在满足Doob可马氏扩张的条件下,马氏自回归方程中,特别是转移矩阵,所有参数如何用平稳列的谱函数中的参数给予显明表示的问题。  The epidemic intensity of the common root rot is affectec very much by the meteorological phenomena. If average temperaturs is above 18°C in flowering stage and relative humidity above 80% the startpoint value of disease epidemic increases. When at the later stage of growth period of wheat hightemperature and humidity environment also appears, in the same year root rot and leaf wilt take place seriously. If the disease index of leaf wilt in flowering stage is about 5%,the epidemic intensity of diseas is of... The epidemic intensity of the common root rot is affectec very much by the meteorological phenomena. If average temperaturs is above 18°C in flowering stage and relative humidity above 80% the startpoint value of disease epidemic increases. When at the later stage of growth period of wheat hightemperature and humidity environment also appears, in the same year root rot and leaf wilt take place seriously. If the disease index of leaf wilt in flowering stage is about 5%,the epidemic intensity of diseas is of the 1 degree.If the index about 20%,the epidemic intensity can reach to the 4 degree. According to the degree of seriousness of disease, the situation of disease on leaves in flowering phase and the temperature condition two prognostic methods for the epidemic of root rot leaf wilt had been researched and developed . The coufidence of these methods is90%and over,which may be used to give instruction of control the root rotleaf wilt.  小麦根腐病的流行强度受气象因子的影响很大,小麦扬花期旬平均气温10℃以上,相对湿度80％以上,病害流行起点值高。在小麦生育后期出现高温高湿的气候环境,当年根腐叶枯发生严重。小麦扬花期病情指数5％左右,当年病害流行强度1级;叶部病情指数20％左右,当年病害流行强度可达4级。据病害发生程度与小麦扬花期叶部病情以及与气象因子的相关研究结果,研制出两种予测根腐叶枯流行强度的方法,置信度90％以上,可用于指导根腐叶枯的药剂防治。   << 更多相关文摘 
相关查询  



