两系稻制种穗期病害发生较重的原因及防治措施

调查分析稻粒黑粉病、穗颈稻瘟等两系杂交稻制种穗期主要病害的发生原因,提出了清除菌源、轮换制种、健身栽培、对口药剂防治等防治措施。     

螟虫长距茧蜂研究进展

本文综述了对螟虫长距茧蜂的研究概况，包括该寄生蜂的主要生物学习性、对玉米螟自然寄生率及田间防治玉米螟效果等。     

稻水象甲发生规律与药剂试验方法的探讨

稻水象甲是国际检疫对象，已经是我国北方水稻产区最重要害虫之一，并且呈迅速蔓延之势。此虫主要借助交通工具作远距离传播。成虫危害叶片，幼虫危害根系。一年繁殖一代但有两个危害高峰。新农药田间药效试验如果针对防治成虫、幼虫或者兼治，应在相应的时间、采取不同的方法进行。     

Evidence that a Leaf-Disk Test Allows Assessment of Isolate-Specific Resistance in Brassica oleracea Crops Against Downy Mildew (Peronospora parasitica)

A rapid resistance/susceptibility test for Peronospora parasitica (downy mildew) was established by inoculating leaf-disks of four Brassica oleracea accessions. Several conditions were tested: disk disinfection or not, agar medium with or without nutrients and with 50 or 100 ppm of benzimidazole. Using disinfected disks placed on agar (no nutrient and benzimidazole at 50 or 100 ppm), the responses of leaf-disks to four isolates were similar to those obtained using the classical cotyledon test, whereas undesired contaminations occurred in all other conditions. The possible effect of the particular leaf used for obtaining the disks was also studied. In each incompatible interaction tested, disks were resistant whatever the leaf used. In compatible interactions, susceptible phenotypes were observed on disks derived from the six lowest leaves, but disks from upper leaves were resistant. The genetic basis of resistance in a F1 hybrid broccoli was assessed, by testing six isolates on an F2 population derived from this hybrid. The cotyledon test only allows inoculation of two isolates per seedling, whereas many isolates can be tested on each plant by using leaf-disks. The segregation of the resistance to each of the six isolates was analysed: two dominant genes (tightly linked) control resistance to all isolates (one to five isolates; the other to only one isolate).     

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.     

Weed:spring barley competition for applied nitrogen in pig slurry

Summary The experiments were carried out in the two spring barley fields of the organic six-course cattle:crop rotation at Foulumgaard, Denmark. The weed density was 300 and 1800 plants m⁻² respectively. Pig slurry was applied by hand in microplots by four methods: broadcasting followed by incorporation, or injected in bands to depths of 5, 10 or 15 cm. Spring barley and weeds were sampled separately six times during the tillering and elongation phase of the spring barley. The effect of application method on dry-matter (d.m.) production, nitrogen uptake and recovery of applied nitrogen in the spring barley and the weeds is reported. Slurry banding halved the weed d.m. and weed N uptake compared with broadcasting, irrespective of weed density. Weeds recovered up to 12% of the applied nitrogen, which made them a significant competitor when the slurry was broadcast and incorporated. Banding by direct injection reduced the slurry:soil contact and the weed:crop competition balance for applied nitrogen moved in favour of the crop. Thus, the crop recovery of applied nitrogen at the end of the sampling period was increased from approximately 45% for broadcast and incorporated to approximately 50% for injected slurry, and coincidental weed recovery was reduced to a maximum of 5%. As the nitrogen supply normally affects plant d.m. production, banding of slurry might well improve crop competitiveness and its tolerance to mechanical weed control.     

南方灭鼠应用稻谷与大米毒饵的比较

生物测定法测得谷壳对复方88-1灭鼠剂的阻滞率为54．3％，光谱分析法测得其对敌鼠钠盐的阻滞率在47．43％—57．00％之间。相同条件下，褐家鼠Rattus norvegicus取食敌鼠钠盐稻谷毒饵量为大米毒饵的2倍多。在南方潮湿的环境下，大米毒饵更易松散、霉变，使其适口性更低。综合考虑认为南方灭鼠使用稻谷毒饵更为合适。     

广东优质籼稻抗稻瘟病育种研究进展

通过对广东优质籼稻品种抗瘟性研究、抗病品种的系谱分析以及抗病育种实践的回顾，综述了广东优质稻抗性育种历史及现状，剖析了优质稻抗瘟育种存在的问题及相应对策。提出开发利用不同稻作系统的抗病资源，构建遗传多样性丰富的抗病优质种质，延长品种抗性寿命及解决品种优质与抗病的矛盾。     

拮抗细菌菌株Bacillus spp.间的相互作用及其对水稻纹枯病的抑制

测定了6个Bacillus spp.和1个Pseudomonas sp.P-13(G-对照菌株)在PPM培养基上的相互作用。在总共42个组合中，有27个组合是可亲和性的。在以B5423为单剂之一的5个组合中，亲和性的组合有4个。在温室条件下通过分批播种，在水稻分蘖盛期喷以B5423-R(B5423的标记菌株，是利福平抗性的突变体)为单剂之一的4个亲和性组合的菌悬浮液，以检测该组合中B5423-R在水稻茎基部的种群数量。结果发现，与单剂B5423-R相比，在应用1～7天内，组合B5423-R B45中，B5423-R的群体数量显著性降低；组合B5423-R B95、B5423-R B77中，B5423-R的群体数量与单剂无显著差异；组合B5423-R B4313中，B5423-R的群体数量在应用1～4天内与单剂无显著性差异，但在应用第7天显著地高于单剂。离体叶片纹枯病痛斑面积的抑制试验表明，与各自的单剂相比，组合B95 B5423及B95 Er77显著地抑制了纹枯病病斑面积；而组合B45 B80、B45 B5423和B45 B95纹枯病病斑面积显著地高于各自的单剂；其余10个组合与各自的单剂无显著差异。     

制约稻粒黑粉病菌冬孢子萌发的关键因素

在相同条件下，从稻田直接收集的病粒中的稻粒黑粉病菌厚垣孢子不能萌发，而取之于仓库中的孢子能萌发。为探明其制约因素，对该病菌进行了光照和浸水时间试验。研究结果表明：稻粒黑粉病菌冬孢子形成后，必须经光照射后，方可进入休眠期；度过5～6个月休眠期的冬孢子，必须浸水48h以上才开始复苏；复苏后的冬孢子必须在光照条件下才能萌发。未完成后熟作用的冬孢子和完成后熟但尚未复苏的冬孢子即使在光照条件下也不能萌发。即稻粒黑粉病菌冬孢子必须经历后熟、休眠、复苏三个阶段后，在适宜的光照与温湿条件下，方可萌发。光照对其冬孢子具有双重作用，促使后熟进入休眠和刺激萌发。