Selection of biological control agents for controlling soil and seed-borne diseases in the field

Different screening methods for selection of biological control agents (BCAs), for controlling soil and seed-borne diseases, are discussed. The shortcomings of laboratory methods focused on mechanism of action are discussed and we conclude that these methods should be used with caution if candidates with multifactorial or plant mediated mechanisms of control are to be obtained. In vitro screens may be useful for specific groups of microorganisms, thus, screens for antibiotics may be relevant for Streptomyces spp., and promising results have been obtained using soil plating or precolonized agar methods to screen for mycoparasitism and competitive saprophytic ability. Experience with screening in the Nordic programme Biological control of seed borne diseases in cereals is summarized. Research in the four participating countries – Finland, Sweden, Norway and Denmark – followed the same paradigm: that of obtaining antagonists, well adapted to different Nordic environments, and developing them as effective BCAs. Potential antagonists were isolated from different sources and in planta screening methods were developed in order to optimize selection of antagonists effective against a range of seed borne pathogens. Screens in the laboratory or greenhouse were followed by screening in the field. The different screening procedures are compared and evaluated.     

昆虫病原线虫的贮存和剂型研究进展

阐述了昆虫病原线虫的贮存原理,介绍业已建立的昆虫病原线虫贮存方法及其优缺点,影响昆虫病原线虫贮存效果的主要因素,并讨论了昆虫病原线虫剂型制备方法。     

Fluorimetric Determination of the Genetic Variability Existing for Chilling Tolerance in Sweet Sorghum and Sudan Grass

Chilling temperatures drastically inhibited the photochemical quenching of chlorophyll fluorescence (q_Q) measured in intact leaves photosynthesizing under steady-state conditions. This effect appeared, however, to be characteristic of chilling-susceptible plant species and was not observed in plants which are known to be chilling-tolerant, indicating that the measurement of q_Q can serve in practice to estimate rapidly the relative chilling tolerance of crop plants. A large number (28) of sweet sorghum (Sorghum bicolor) and Sudan grass (Sorghum sudanense) genotypes were screened for chilling tolerance using this rapid q_Q method. Although sweet sorghum and sudan grass obviously behaved as chilling-sensitive plants, a considerable variation for chilling susceptibility was observed among the different genotypes tested. Some sweet sorghum varieties, such as ‘Dale’ and ‘Keller’, and most of the sudan grass varieties appeared to possess a certain degree of resistance towards low temperature stress, indicating the existence of useful germplasms in Sorghum for improving stress tolerance.     

高海拔区域夏秋季双孢蘑菇覆土材料筛选

以双孢菇品种As2796为试材,研究双孢蘑菇覆土材料中添加一定比例的泥炭土、发酵棉籽壳、麦衣等材料后对双孢菇生长的影响。结果表明：添加一定比例的泥炭土、发酵棉籽壳、麦衣等材料后能有效改善覆土结构,出菇快、菇蕾整齐,出菇期分别较对照提前2~7 d。较常规覆土处理增产0.25~1.60 kg.m-2,其中泥炭N-3及综合覆土配料Z-3覆土处理增产率为17.98%及10.67%。     

水稻病毒病田间防控方法的研究进展

水稻病毒病防控方法的研究是我国一项重要课题,关系着我国粮食生产,目前没有很好的药剂去防控水稻病毒病,但田间防控方法上取得了一定的进展。     

Integrating new soybean varieties for soil fertility management in smallholder systems through participatory research: Lessons from western Kenya

The aim of this paper was to understand the process of selecting soybean (Glycine max [L.] Merr.) promiscuous varieties by smallholders for soil fertility management in western Kenya. Eight varieties were screened on 2.5 m × 3 m plots that were managed according to farmers’ practices and evaluated through participatory monitoring and evaluation approaches. Farmers selected preferred varieties and explained their reasons (criteria) for making the selections. Seven promiscuous varieties had better yields than a local one. Farmers’ selection criteria fell into three broad categories relating to yield, appearance and labour. Selection criteria were not primarily aimed to improve soil fertility. This created a challenge to embed the new varieties within the local farming systems for soil fertility improvement. This study shows that farmer criteria for selecting varieties overlapped with scientific procedures. We propose co-research activities targeted to strengthen farmer experimentation skills, their understanding on N addition, and the role of P.     

除草剂阿特拉津污染地下水的生物治理研究

利用从农药厂阿特拉津生产车间排污口污泥中分离出的菌种AT菌，进行了农药阿特拉津污染地下水的微生物治理模拟实验研究。结果表明，在实验条件(t=10℃，pH＝7．5)与野外含水层的条件基本一致的情况下，难于生物降解的污染物质阿特拉津的一次投菌降解率达到26．29％；同时环境因素也随着AT菌作用的变化而变化，其中，DO、Eh、pH随AT菌作用的加强而其值减小。另外，设计了细菌的投放方式以模拟野外条件下的菌种投加条件。模拟实验为野外的原位治理提供了理论和方法依据。     

Use of mathematical modeling and its inverse analysis for precise assessment of pesticide dissipation in a paddy environment

The extrapolability of the lysimeter test as a dissipation simulator in an actual paddy field was evaluated using mathematical models and their inverse analyses for predicting pesticide fate and transport processes in paddy test systems. As a source of experimental data, a four-year comparative experiment in lysimeters and paddy fields was conducted using various paddy pesticides. First, the dissipations for various active ingredients in granule pesticides under submerged applications were statistically compared using simple kinetic modeling. Second, the dissipation pathways, unobserved experimental components, and effect of the experimental setting were evaluated using a higher tier mathematical model with a novel inverse analysis protocol. Finally, owing to experimental constraints, the unobtainable parameters were extracted from the laboratory container test before being transferred to compare the outdoor experimental data under different formulation types.     

5种宿根花卉品种性生长习评价及栽培研究

为了丰富北京园林绿地应用植物种类、丰富景观、稳定植物群落,试验从北京地区及其他城市引种约40种宿根品种,经过2个生长周期的适应性观察,筛选出能越冬、夏季表现良好、有较好观赏效果的匍枝亮绿忍冬、‘矮黄金’一枝黄花、‘瀑布’矾根、‘面包师’厚叶福禄考、‘霍特’匍匐婆婆纳5种宿根品种,进行了物候和适应性观测试验,对自然株高、花果期、花色、绿期等8项指标进行了综合评定,并进行了繁殖栽培技术和管理等研究。     

Identification of resistance to Uromyces pisi (Pers.) Wint. in Pisum spp. germplasm

A germplasm collection of 2759 pea accessions was screened for resistance against Uromyces pisi (Pers.) Wint. All accessions displayed a compatible interaction (high infection type) both in adult plants under field conditions and in seedlings under growth chamber conditions, but with varying levels of disease reduction. The identified resistance was based on reduction of disease severity with no associated host cell necrosis, which fits the definition of Partial Resistance. No complete resistance or incomplete resistance based on hypersensitivity was observed.