不同黄瓜材料对枯萎病的抗性评价

以危害我国黄瓜的优势枯萎病生理小种4为供试菌源,运用室内苗期人工接种和田间成株期病圃检测2种方法对43份黄瓜材料进行了枯萎病的抗性评价,苗期接种筛选出抗病材料7份,中抗材料16份,感病和高感材料20份。其中抗(含中抗)材料占53.5%,感病材料占46.5%。欧洲血缘的抗病(中抗以上)材料占39.5%;华北和日本血缘的抗和中抗材料占13.9%。成株期田间病圃的鉴定结果与苗期接种基本一致,符合率达86.7%。说明苗期接种结果准确,接种方法可靠。同时还表明了黄瓜种质资源中蕴藏着对改良枯萎病抗性有利用价值的基因资源,其中欧洲黄瓜抗源较丰富,华北和日本类型的黄瓜枯萎病抗源相对匮乏。     

贵州省喀斯特地区解决小流域粮食问题途径

俄脚河小流域,因长期掠夺性开发利用,使植被屡遭破坏,生态环境恶化,加上落后的生产方式,造成粮食单产低,粮食产量严重不足,根据小流域的特点,通过科学配置各项治理措施,综合治理和控制水土流失,恢复生态平衡,改善粮食生产的外部生产条件,建设高标准的水平梯田,提高地力,改变传统的耕作制度,控制人口增长,大力推广良种和高产栽培技术,促进粮食的高产、稳产,为喀斯特地区解决粮食问题提供了较好的模式。     

城口鱄鱼的食物选择性研究

本文研究了在常温静水条件下,城口鱄鱼对鱼粉、肉粉、豆粕、玉米麸、花生饼、小麦麸等饲料原料的食物选择性。试验结果表明,城口鱄鱼对于这六种饲料原料的选择性表现为:鱼粉肉粉豆粕花生饼小麦麸玉米麸。     

利用雌性单株建立蓖麻雌性系的三种方法比较

比较了三种由雌性单株建立蓖麻雌性系方法：（１）利用环境高温处理ＮＥＳ型雌性单株诱导雄花建立雌性系,是比较成熟的方法,但对日均温要求较高。（２）利用植物生长调节剂处理ＮＥＳ型雌性单株诱导雄花建立雌性系,该法成功的可能性较大,对环境条件要求也不高,如积极探索有望早日成为比较成熟的方法,目前已有一定的进展。（３）利用组织培养无性繁殖Ｎ型雌性单株建立雌性系,该法也有一定的可能性。值得进一步探索。     

小篷竹群落邻体干扰指数的研究

运用邻体干扰指数模型,分析小蓬竹群落种内、种间竞争强度,确立小蓬竹群落的竞争干扰因子。结果表明,在小蓬竹群落中,对小蓬竹干扰指数最大是猴樟,其次是小蓬竹本身。在自然情况下的群落演替过程中,猴樟种群将占优势,最终小蓬竹将在小蓬竹群落彻底消失。     

Genetics of stem rust resistance in the durum wheat accession ‘Reichenbachii’

Summary Inheritance of seedling reactions to cultures of races TLM and MBCT of Puccinia graminis f.sp. tritici was studied in crosses of the resistant durum Reichenbachii with susceptible Marruecos 9623 and DZ04-118. The Chi-square test for goodness of fit was used to analyze segregating populations. Two independent recessive genes appeared to control resistance of Reichenbachii to both TLM and MBCT. Depending upon the cross, the two genes interacted cumulatively to condition immunity or higher levels of resistance than either parent conditioned singly. There was no evidence of maternal influence on the inheritance of resistance. Resistance genes in Reichenbachii were recessive; therefore, breeders should consider the use of relatively large F₂ populations to effectively transfer these genes to cultivars with good agronomic characteristics.     

Inheritance of the Powdery Mildew Resistance Gene Pm9 in Relation to Pm1 and Pm2 of Wheat

The inheritance of the powdery mildew resistance gene Pm9 originating from the hexaploid spring wheat cultivar ‘Normandie’ was analyzed in relation to Pm1 and Pm2. Two leaf segments of individual P_1?, P_2?, F_1? and F₂-plants of the cross ‘Normandie’ (Pm1, 2, 9) בFederation’ (no known Pm gene) were inoculated separately with two powdery mildew isolates. Using powdery mildew isolate No. 6 virulent for Pm1 and Pm2 but avirulent for Pm9, a 1 resistant (r): 3 susceptible (s) F₂-segregation was found for the Pm9 gene. Using powdery mildew isolate No. 3 virulent for Pm1 and Pm9 but avirulent for Pm2, a 3 (r): 1 (s) F₂-segregation was found for the Pm2 gene. Combining the data of both experiments (leaf segments of identical plants had been used), a 9 (sr): 3 (ss): 3 (rr): 1 (rs) segregation resulted for the F₂ of this cross: therefore, independent inheritance of the genes Pm2 and Pm9 can be concluded. Similarly, the cross ‘Mephisto’ (Pm1, 2, 9) בAmor’ (no known Pm gene) was analyzed. The Pm9 gene again showed a monogenically recessive inheritance, whereas Pm1 showed a monogenically intermediate segregation upon inoculation with powdery mildew isolate No. 9a virulent for Pm2 and Pm9 but avirulent for Pm1. Combining the single gene segregations, linkage between both genes was found among the progenies. A distance of 8.5 cM was calculated. Analyzing a set of spring wheat cultivars with seven defined powdery mildew isolates, the presence of Pm1, Pm2 and Pm9 in these lines was verified; in most cases, Pm1 occurred together with Pm9.     

MEASUREMENT ON THE SOUND POWER LEVEL FOR MECHANICAL NOISE

Because of changeable distribution of noise fields in different room and the different absorption coefficients of walls and ceilings, average absorption coefficient of room surface hase to be estimated,which is really a great trouble . Now,this problem is solved,because,as discribed in this paper, the mechanical noise of the A weighted sound power level can be calculated after the absorption coefficient and environmental correction value is obtained. Experiences show that the result is accurate enough for engineering practice.     

Growth of wheat leaf rust colonies in susceptible and partially resistant spring wheats

Summary The average size of wheat leaf rust colonies, measured using epifluorescence microscopy was significantly larger in the highly susceptible genotype Morocco than in the susceptible genotype Kaspar and the partially resistant genotypes Westphal 12A, Akabozu and BH 1146. This was already so three days after inoculation. Colony growth in partially resistant genotypes was continuously retarded compared to colonies in the highly susceptible genotype Morocco. No evidence was found for an initial inhibition of the growth of colonies in partially resistant genotypes. In partially resistant genotypes formation of uredial beds and sporulating areas started at a smaller colony size than in susceptible genotypes. Wheat leaf rust colonies in primary leaves of all genotypes studied were much larger than colonies in flag leaves measured at the same number of days after inoculation. Growth and sporulation of not intertwined colonies was not influenced by either a high or a low number of neighbouring colonies.     

外源激素诱导雷竹鞭芽萌发效果分析

用外源激素诱导雷竹侧芽培养，结果表明，不同季节侧芽萌发率差异极显著，以春季（２月２０日）的７０％为最高，秋季（１０月２０日）的５７％次之，夏季（５月１７日）的２２％为最低；不同鞭龄的侧芽萌发率不同，春秋季以４年生最低，１年生、３年生次之，２年生最高；不同的年龄和ＢＡ用量萌发率差异水平不尽相同；２年生竹鞭，用不同激素种类和用量处理，萌发率均未达到差异显著水平。