土壤环境因素对棉花黄萎病菌微菌核存活的影响

 试验研究了土壤温度、湿度、pH值和有机质对棉花黄萎病菌微菌核存活的影响。结果表明:40、30和0℃对微菌核土壤存活影响较大,10和20℃影响较小,尤其以10℃影响最小;土壤含水量越高,对微菌核存活影响越大,在含水量低于15%时,对存活影响较小,尤其以5%的含水量影响最小,表明微菌核对土壤干旱逆境具有较强的抵抗能力;pH值低于5.5或高于8.5的土壤条件对微菌核存活影响较大,pH值为6.5~7.5影响较小;土壤有机质含量越高,微菌核存活率越低,含量低,存活率高。本研究结果表明,只要改善和控制棉花黄萎病菌土壤存活的生态条件,就可以有效地减少土壤存活菌量,达到控制病害发生与发展的目的。     

Inhibition of germination of sporangia of Peronospora hyoscyami by cation deprivation: the effects of substrate and chelating agents

Germination of sporangia of Peronospora hyoscyami de Bary (tobacco blue mould) was affected by the germination substrate. Washed sporangia germinated freely in water on glass slides, but failed to germinate on agarose. Germination was reduced on detached tobacco leaves, being lower on cv. Hicks Q46 than on cv. ZZ100. Inhibition of germination by agarose was reversed by the addition to the inoculum of an extract obtained by centrifuging a suspension of non-living, powdered torula yeast Candida utilis (Hennenberg) Lodder & van Rij. Yeast extract also improved germination in vivo. The siderophore rhodotorulic acid, the chelating agents ferric and sodium citrate, and riboflavin combined with calcium and magnesium salts, also stimulated germination of sporangia on agarose. The chelating agent ethylenediaminetetraacetic acid (EDTA) inhibited germination on glass slides. Inhibition by EDTA was partially reversed by the addition of ferric salts. The inhibition of germination by agarose and stimulation by additives may have been due to effects on the availability of cations to sporangia of P. hyoscyami. The reduction in germination on tobacco leaves may have involved a similar mechanism.     

Effect of temperature on epidemiological parameters of Puccinia lagenophorae

The effect of temperature on latent period and aeciospore production of Puccinia lagenophorae on Senecio vulgaris was determined in small-scale experiments under controlled conditions. A clear effect of temperature on latent period was demonstrated. Latent period decreased exponentially with increasing temperature. Both total aeciospore production and net reproductive number increased linearly with increasing temperature in a range from 10 to 22°C. The three parameters were incorporated in models to determine the effect of temperature on epidemic development. The present study suggests an increase in the exponential growth rate, r , and the velocity of focus expansion, V , with temperature. This increase in epidemic development was caused mainly by the effect of temperature on latent period and on net reproductive number. The effect of temperature on the sporulation curve appeared to be less important.     

行间种植不同草种对幼龄苹果园土壤特性的影响

于苹果园建植第一年春季,果树行间分别种植不同草种,以清耕的土壤为对照,研究果园土壤温度、含水量、pH值、有机质及N、P、K的变化。结果表明,种草后,夏季高温时土壤温度降低、日变幅减小,含水量增加,生长季结束时,果园土壤pH下降,碱解N、全N、速效P、全P、有机质含量增加,而除种植红三叶的土壤速效K显著(P<0.05)升高外,其余处理全K、速效K均无显著变化;种草后对不同深度土壤肥力的影响不同,马蹄金对土壤N、P和狗牙根与高羊茅对有机质的影响在0~20 cm内表现一致,而种植多年生黑麦草、狗牙根、紫羊茅的0~10 cm土壤碱解N、全N、全P和种植红三叶、紫羊茅的0~10 cm土壤有机质升高幅度较10~20 cm大,多年生黑麦草、高羊茅、紫羊茅、红三叶、白三叶的速效P,红三叶和高羊茅的碱解N、全N,马蹄金、多年生黑麦草、白三叶的土壤有机质0~10 cm土壤升高幅度较10~20 cm小,白三叶10~20 cm土壤碱解N增加幅度较0~10 cm小,全N则反之;草种不同对土壤作用不一,马蹄金对土壤肥力改善作用最大,红三叶、白三叶次之,而狗牙根、高羊茅较差。说明种草后可改善土壤性状,而草种是影响果园种草效益的关键因素。     

Some Aspects of Chemical Control of Soil-borne Pathogens

The effect of a soil fumigant on soil-borne pests and pathogens depends largely on a sufficient distribution through the top soil and the availability of the fumigant or the biologically active degradation products in the water phase. Nearly all the fumigants are dispersed in the soil mainly in the vapour phase and therefore the amount of air between the soil particles is very important. Consequently on light soils it is relatively easy to obtain an efficient control, but on heavy or wet soils and on soil types with a high humus content it is rather difficult to get reliable results. The concentration of the fumigant in the upper few cm. of the soil is often insufficient to get good control after injection of the material at 15–20 cm. depth. The effect may be improved by using a plastic cover or a «split plot>> application.
The elimination of most of the fumigant, to avoid a phytotoxic effect is a cause for concern on wet soils and on soil types with a high organic content. Factors influencing the decrease of the fumigant residue in the soil are discussed. The soil fumigant application gives rise to important changes in the whole ecosystem in the soil. Information on the influence on non-target organisms is scarce. The application of dichloropropene and of chloropicrin may lead to a noticeable effect on the nitrificating bacteria.
The soil application of fumigants may give rise to residues in plants of the parent chemical or, to a larger extent, to residues of metabolites e.g. Br^- after soil disinfection with Br^- containing fumigants such as methylbromide, EDB¹), etc. The enrichment of the soil with Br^- may cause phytotoxic effects on susceptible crops such as carnations. The fate of the metabolites arising from dichloropropene and related compounds has not been fully clarified.     

南宁市桑白粉病病原菌种类鉴定

桑白粉病是桑树的重要病害,分为桑里白粉病和桑表白粉病。通过形态特征观察和ITS、D1/D2序列分析,明确桑里白粉病的病原菌为桑生球针壳Phyllactinia moricola;桑表白粉病的病原菌为桑白粉菌Erysiphe mori。桑钩丝壳Uncinula mori是桑白粉菌的异名。     

寄主植物对棉蚜乙酰胆碱酯酶的影响

通过生物测定和生化分析研究了5种不同寄主植物上的棉蚜种群对灭多威的敏感性，乙酰胆碱酯酶（AChE)活性及灭多威对AChE的抑制作用，结果发现，取食石榴和花椒的棉蚜AChE活性最高，是冬青上棉蚜（最低）的2．00倍和3．33倍，说明寄主植物可以影响棉蚜AChE的活性，灭多威对不同寄主植物上的棉蚜个体的AChE进行抑制后，发现棉花和冬青上的棉蚜种群中AChE对灭多威不敏感的棉蚜个体多于花椒，木槿和石榴上的棉蚜种群，这与棉花及冬青上的棉蚜对灭多威耐药性较其它三种强的趋势近似，表明AChE敏感度的降低是棉蚜对灭多威产生抗药性的原因之一。     

Relationships between establishment of Erysiphe cruciferarum and soluble amino-acids in leaves of Brussels sprouts

The ability of Erysiphe cruciferarum to establish infections on detached foliage and button leaves of two F_l cultivars of Brussels sprouts grown in the field was examined under standard conditions. Consistently more infections developed on Goldmine than on Ulysses. On foliage leaves of both cultivars the numbers of infections fluctuated from week to week but generally increased with time on samples taken from September to December. On Goldmine, more infections developed on the oldest foliage leaves than on those of intermediate position on the stem and only infections on the mature leaves sporulated well. The number of infections increased progressively on leaves further into the sprout buttons of both cultivars. Fungal establishment on foliage and button leaves of Goldmine was related to the amino-acid content of comparable uninoculated leaves.     

不同基质及颜色背景对井上蛀果斑螟产卵生物学的影响

为明确产卵基质和环境颜色对井上蛀果斑螟成虫产卵生物学特性的影响,在室内条件下,研究了井上蛀果斑螟对PE保鲜膜、硫酸纸、蜡纸3种介质的产卵选择性和绿、橙、红、黄、粉、紫、蓝7种不同颜色背景对成虫寿命、产卵期、产卵量和卵孵化率等生物学参数的影响。结果表明:井上蛀果斑螟在硫酸纸上的累积落卵量最高,对其选择率也最高,分别为130.33粒和58.67%;蜡纸最低,分别为29.00粒和8.00%。绿色背景下雌、雄虫寿命均最短,分别为8.55 d和7.65 d;雌虫寿命在红色背景下、雄虫寿命在黄色背景下最长,分别为15.22 d和15.50 d。粉色背景下雌虫产卵前期较短,为1.50 d,显著短于除绿色背景外的其余处理,红色背景下产卵前期最长,为4.50 d;蓝色背景下雌虫的产卵期最短,为8.25 d,橙色背景下产卵期最长,为17.25 d。粉色背景下雌虫单雌产卵量为73.75粒,显著高于除橙色背景外的其余处理;红色背景下单雌产卵量最少,为28.60粒。绿色背景下卵的发育历期较长,为5.71 d,显著长于除红色和黄色背景外的其余处理;蓝色背景下卵的发育历期较短,为4.66 d。红色背景下卵孵化率较高,为79.53%,其次为紫色背景的79.06%,绿色背景下卵孵化率最低,为54.08%。产卵基质和环境颜色可显著影响井上蛀果斑螟的产卵生物学特性。     

寄主植物对水椰八角铁甲生长发育和繁殖力的影响

研究了3种棕榈科植物对水椰八角铁甲生长发育的影响,结果表明：水椰八角铁甲取食不同棕榈科植物,其成虫寿命、存活率及产卵量差异显著,取食金山葵［Syagrus romanzof fiana(Cham.) Glassman］的成虫寿命长,产卵量大,存活率高。3种植物上的蛹历期均在6 d左右,完成1代所需时间在金山葵上约需(40.18±1.10)d,大丝葵(Washingtonia robusta H. Wendl.)和海枣(Phoenix dactylifera L.)上分别为(43.48±1.00)d和(45.02±0.89)d。单头雌虫产卵量以金山葵上最高,为(104.55±6.20)粒,大丝葵和海枣上较低,分别为（44.13±2.77）粒和(34.89±4.14)粒。幼虫取食不同寄主发育为成虫,雌雄比以大丝葵上最高,为2.33〖DK1〗∶1,金山葵和海枣上较低,分别为1.33∶11和1.43∶11。在金山葵、大丝葵和海枣上的实验种群趋势指数分别为47.14、5.64和6.43。     

禾谷镰刀菌在小麦穗部侵染过程的细胞学研究

 采用扫描和透射电镜技术系统地观察了禾谷镰刀菌(Fusarium graminearum)在小麦穗部的侵染过程。接种后6~12 h,分生孢子在小麦穗部的任何部位均可萌发,每个孢子可产生1至多个芽管,新产生的芽管并不立即入侵寄主组织,而是在寄主体表生长扩展;接种后36~48 h观察,小穗颖片、外稃、内稃的内侧和子房的表面形成了密集的菌丝网,然而在小麦穗轴表面、颖片和内稃的外表面,菌丝生长缓慢、分布稀疏,但颖片外表边缘的菌丝可跨越边缘扩展到颖片的内表皮上;接种后36 h,寄主体表菌丝产生入侵菌丝,以直接入侵方式由颖片、外稃、内稃的内侧及子房的顶部侵入寄主组织体内,随后,菌丝以胞间和胞内生长的方式向下扩展;接种后4~5 d,菌丝由上述组织扩展到达穗轴后,在穗轴内沿微管束组织和皮层组织向上和向下扩展,延伸到相邻小花,随菌丝在小麦穗部组织内不断地生长扩展,使得寄主细胞坏死、解体,并最终导致整个麦穗的枯死。     

Identification of W-type and R-type isolates of Pseudocercosporella herpotrichoides

W-type isolates of Pseudocercosporella herpotrichoides grown on a maize-based agar and exposed to near- ultra-violet radiation at c . 13°C produced a greenish black colour, whilst R-type isolates produced a pink or pale brown colour in the agar medium. More colonies from directly plated lesions or from spore suspensions could be recognized as P. herpotrichoides and could be more easily differentiated as W-type or R-type or as mixtures of both by colour production on maize agar (MA) than by colony morphology on potato dextrose agar (PDA), despite the presence of other fungi. Isolates with intermediate morphology on PDA were positively identified as W-type or R-type on MA; their pathogenicities to wheat and rye seedlings were usually similar to those of W-type or R-type isolates with typical colony morphology, confirming their identification on MA. Drops of mixed suspensions of W-type and R-type spores on PDA formed fast-growing colonies with smooth margins which sometimes had slow-growing sectors with feathery margins. Drops of the same mixtures on MA formed greenish black colonies which sometimes had pink or pale brown sectors. However, when these mixtures were spread onto MA, W-type and R-type colonies could easily be differentiated by colour.     

Effect of Margosan-O on the development of the leafhopperasymmetrasca decedens

The effect of Margosan-O, a formulation of a natural insecticide obtained from the neem (Azadirachta indica A. Juss) tree, on the development of the leafhopperAsymmetrasca decedens (Paoli), was investigated by testing insect performance (i) on cotyledons ofGossypium hirsutum cotton seedlings treated with different concentrations; (ii) on cotton seedlings stood with their petioles in different aqueous dilutions of Margosan-O and recording mortality until the adult stage; and (iii) determining the repellent effect on adults by recording their location on treatedvs untreated cotyledons in choice and no-choice situations. In foliar and in systemic treatments with 2% Margosan-O, practically none of the leafhoppers reached the adult stage. As the concentrations were lowered there was a gradual rise in the percentage of adults emerging; on untreated cotyledons 60-80% of the adults emerged. Feeding was zero or very low at high Margosan-O concentrations. Adult leafhoppers settled in significantly higher numbers on untreated than on treated cotyledons in both choice and no-choice experiments.     

Deltamethrin: A neurophysiological study of the sites of action

Recent experiments on the mode of action of pyrethroids have indicated that those pyrethroids containing an α-cyano phenoxybenzyl group may act on GABA-mediated chloride channels. The crayfish stretch receptor neuron provides a useful preparation for examining the effects of pyrethroids on these channels and on sodium channels. The lowest concentration of deltamethrin to have an effect on sodium channels was 10⁻¹² M, but the response of the preparation to GABA appeared to be unaffected by concentrations of deltamethrin up to 10⁻⁷ M. Although 10⁻⁶ M deltamethrin had a slight effect on the GABA response of the dactyl abductor muscle, it appears that the majority of the effects of cyano pyrethroids in invertebrates could be accounted for solely by their action on sodium channels.     

寄主与粮粒对雅脊金小蜂寄生和发育的影响

从三级营养关系出发,研究了不同粮食（小麦和玉米）和寄主（米象和玉米象）对雅脊金小蜂发育和寄生的影响。结果表明：4个三级营养系统中雅脊金小蜂实验种群在4种虫源寄主中均能正常发育,其卵-成虫的发育历期在4种虫源寄主中由短至长依序为：玉米粒-玉米象〈小麦粒-玉米象〈小麦粒-米象〈玉米粒-米象;4种蜂源中雅脊金小蜂对小麦中的米象或玉米象的寄生率、刺死率和总致死率均显著高于对玉米中的米象或玉米象。因此用雅脊金小蜂控制小麦中的米象或玉米象,其效果较之玉米中的米象或玉米象的效果更好。     

Effect of certainBrassica plants on biology of the cabbage aphidBrevicoryne brassicae under laboratory conditions

The development time, mortality, survivorship and reproduction of the cabbage aphidBrevicoryne brassicae (L.) were evaluated on detached leaves of sixBrassica species (cabbage cv. ‘Yalova 1’, cauliflower cv. ‘Early Snowball’, broccoli cv. ‘Marathon’, turnip cv. ‘Antep’, rapeseed cv. local variety, and wild mustard) at a constant temperature of 20°C. Total development time ofB. brassicae was the shortest (8.9 days) on cauliflower and the longest (10.4 days) on cabbage. Mortality of immature stages varied from 16% on cabbage to 88% on turnip. Longevity of the cabbage aphid was the shortest (6.2 days) on mustard, and the longest (21.8 days) on cauliflower. The net reproductive rate was highest (35.98) on cauliflower, and lowest (1.89) on turnip. The intrinsic rate of increase was 0.2345 on cauliflower, followed by 0.2009 on cabbage, 0.1976 on broccoli, 0.1662 on mustard, 0.1357 on rapeseed, and 0.0465 on turnip. Cabbage, cauliflower and broccoli were susceptible host plants for the cabbage aphid. Rapeseed, turnip and mustard showed resistance to the pest.     

Analysis of the effects of selected gronomic factors on the dynamics of the take- all disease of wheat in field plots

Linear models were used to investigate the effects and interactions of treatments for the control of disease in multifactorial experiments on the dynamics of the take- al disease of wheat. Analyses were based on repeated measures of disease on second successive winter wheat crops in three successive se sons. The treatments were date of sowing, presence or absence of triadimenol-containing seed treatment, autumn nitrogen and chloride applications, timing of early spring nitrogen and total spring nitrogen applications. The effects of treatments were investigated on line and quadratic trends of disease increase and on the integral amount of disease over time. Different disease variables were used to express disease relative to the total and diseased plant populations. The effects of treatments on absolute and relative numbers of diseased roots per plant were also analysed. During three se sons when disease was never severe, the effects of the treatments were shown to be variable. Late sowing consistently reduced disease during the early stages of the epidemic (in the winter months). The effect of late sowing in reducing disease, however, persisted through to the end of the growing se son in only one of the 3 years of the study. autumn nitrogen application and Baytan seed treatment (containing triadimenol) also reduced disease in some seasons. The presence of an effect for either was dependent on sowing date and was most evident on the proportion of diseased roots relative to the diseased plant rather than the total plant population.     

几种葡聚寡糖激发子及其衍生物生物活性的比较

 利用大豆子叶法对人工合成的几种葡聚寡糖激发子及其衍生物的生物活性进行测定,比较其结构与活性之间的关系。研究证明,葡聚七糖的活性明显高于六糖,葡聚六糖及其衍生物的EC₅₀值高于葡聚七糖及其衍生物。葡聚七糖、葡聚六糖还原端附加烷基对其EC₅₀值均没有明显影响。葡聚寡糖多聚体的活性要高于单一葡聚寡糖。水杨酸七糖活性高于葡聚七糖。     

A study of the possible interconversion of hexachlorocyclohexane stereoisomers on chickpea

A field trial was conducted to study (i) whether there is interconversion of stereoisomers of hexachlorocyclohexane (HCH) on a plant and (ii) the rate of dissipation of lindane on chickpea in a sub-tropical climate. The lack of formation of the beta and delta isomers on application of pure alpha- or gamma-HCH showed that these stereoisomers of HCH did not interconvert on chickpea. The residues of the alpha and gamma isomers dissipated rapidly on chickpea leaves with half-lives of three and four days respectively.     

寄主植物对烟粉虱后代种群抗性相关酶活性的影响

比较了取食不同寄主植物的烟粉虱后代羧酸酯酶和乙酰胆碱酯酶的活力。结果表明:寄主植物对烟粉虱羧酸酯酶和乙酰胆碱酯酶(AChE)活力影响显著,取食不同寄主植物的烟粉虱后代羧酸酯酶和AChE活力差异显著。在试验的甘蓝、花菜、小白菜和苘麻4种寄主中,取食小白菜、甘蓝的烟粉虱后代种群羧酸酯酶的酶活力显著高于取食花菜和苘麻的,取食小白菜的酶活力最高,是取食苘麻的3.90倍。取食甘蓝的后代种群AChE的酶活力最高,取食苘麻的后代种群酶活力最低;取食花菜与小白菜、小白菜与苘麻之间没有明显差异,但甘蓝与其他寄主上的烟粉虱后代种群之间的差异均达到了极显著水平。取食甘蓝、花菜、小白菜的后代AChE OD值分别为取食苘麻的2.85、2.39倍和1.07倍。