Evaluation of Setaria cervi antigen in the diagnosis of human filariasis

Bovine filariid worm (Setaria cervi) antigen was evaluated for the immunodiagnosis of human filariasis. Patients with manifestations of filarial infection; [1) microfilaremia cases, (2) chronic clinical cases, (3) tropical pulmonary eosinophilia (TPE) cases) were taken for the investigations along with (4) normal endemic and non-endemic human subjects. CIEP, IFAT and ELISA tests were employed for detection of serum antibodies. There was a high degree of sensitivity shown by IFAT (1:64-1:256) and ELISA (1:200-1:20,800) in microfilaraemia cases and higher in chronic clinical cases with IFAT (1:128-1:1,024) and ELISA (1:12,800-1:102,400). Only one TPE case showed positive titre by IFAT (1:64) and ELISA (1:200) whereas sera from controls and patients with helminth infections did not show positive titres (1:100). In the case of CIEP, positive reaction was seen in only one case from group I.     

Amoebiasis in foreign students

A total of 2,883 foreign students at the age of 18-30 years were examined for amoebiasis after their arrival to Czechoslovakia. Stool examinations revealed the presence of Entamoeba histolytica in 112 of them (3.9%). Students from 38 countries were found to be infected with this parasite. In a set of 2,064 students from these countries E. histolytica prevalence in stool was 5.4%. There were greater differences in the prevalence between individual countries inside a geographical region than between individual geographical regions. The highest E. histolytica prevalence in stool was found in students from tropical and southern Africa (6.7% of 745 examined) and the lowest in students from South-eastern Asia (3.1% of 321 examined). In a simple cross-section study, antibodies against E. histolytica were detected by enzyme-linked immunosorbent assay (ELISA) in the sera of 1,001 persons. Antibodies were detected in 7.9% of students at the following titres: 1:200 in 4.5%, 1:600 in 1.5%, 1:1,800 in 1.9%. Antibodies occurred more frequently in students carrying E. histolytica cysts (X2 = 14.9). Titre of ELISA antibodies in patients with confirmed liver abscess was higher than 1:1,800. counterimmunoelectrophoresis (CIEP) test was used for serum examinations of patients who had been demonstrated by ELISA to be seropositive and of those carrying E. histolytica cysts. In a set of 170 patients CIEP antibodies were also more frequent in those carrying E. histolytica cysts (X2 = 26.95). A comparison of the results of ELISA and CIEP tests in the same patients revealed that CIEP antibodies were more dependent on the actual parasitization with E. histolytica than ELISA antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluations of antibody levels in Toxoplasma infection by the immunofluorescent antibody test and ELISA test

In this study 292 sera were screened by the IFAT. 46 sera with variable IFAT titres were tested with ELISA Reagent Set and microtitration tests. A comparative evaluation of the specificity and reliability of ELISA method with that of IFAT for the detection of Toxoplasma infection was done.     

两种水稻种子处理悬浮剂对旱直播水稻生长的影响

为了探究水稻种子处理悬浮剂(FS)对旱直播水稻生长的影响，本研究采用11%的氟唑环菌胺·咯菌腈·精甲霜灵FS和18%的噻虫胺FS对三系籼型杂交稻广8优1973进行包衣，通过标准发芽试验、Q2测定、田间农艺性状调查、考种及测产，比较研究了两种FS在旱直播条件下对种子活力、水稻田间农艺性状及产量的影响。结果表明：在实验室条件下，采用11%氟唑环菌胺·咯菌腈·精甲霜灵FS和18%噻虫胺FS以药浆体积与种子质量比(药种比)为1:50的比例(即1 mL药剂处理50 g种子)将药剂稀释后进行拌种，处理后的标准发芽势、发芽率及萌发启动时间(IMT)均与对照无显著差异，但其理论萌发时间(RGT)相较于空白对照(CK)显著缩短，且氧气消耗速率(OMR)相较于CK每小时分别提高了1.33%和1.38%，呈显著性差异，说明经过FS处理的种子可以促进水稻种子呼吸，能够有效提升水稻种子活力，其中经过18%噻虫胺FS处理的水稻种子IMT、RGT及OMR值的表现均优于11%氟唑环菌胺·咯菌腈·精甲霜灵FS处理；在旱直播条件下，水稻种子按药种比1:50经过两种FS处理后，其田间表现均优于CK，其中：成秧率提升27.6...     

转基因玉米表达的Cry1Ab、PAT和EPSPS蛋白对日本通草蛉幼虫的安全风险评估

为评价我国自主研发的转基因玉米表达的Cry1Ab、PAT和EPSPS蛋白对日本通草蛉Chrysoperla nipponensis幼虫生长发育的安全风险,通过将外源蛋白混入日本通草蛉人工饲料中的方法,以加入砷酸二氢钾(KH_2AsO_4)的饲料为阳性对照,研究了日本通草蛉幼虫取食后的生长发育状况。结果表明:日本通草蛉取食含Cry1Ab和EPSPS蛋白饲料的幼虫发育历期、茧期、结茧率、羽化率及成虫体重等生物学参数与取食正常饲料处理相比均没有显著差异;而取食含PAT蛋白饲料的幼虫发育历期和结茧率分别为10.7 d和96.6%,与取食正常饲料的对照11.1 d和89.9%差异显著,即饲料中添加PAT蛋白显著提高了幼虫的存活率和发育速率;取食含KH_2AsO_4饲料的日本通草蛉幼虫不能存活到茧期,说明KH_2AsO_4具有显著的杀虫活性。ELISA检测结果表明,取食了分别添加有3种外源蛋白饲料的日本通草蛉幼虫体内可以检测到相应的Cry1Ab、EPSPS和PAT蛋白,含量分别为2 758.8~5 210.7、35 018.0~54 426.6、16.8~149.8 ng/g。表明转基因玉米所表达的Cry1Ab、EPSPS和PAT蛋白对日本通草蛉幼虫没有显著的不利影响。     

Hemocyanin lipid uptake in Polybetes pythagoricus is altered by fenitrothion

The spider very high density lipoprotein (VHDL), which contains hemocyanin as the major apoprotein, transports most of the circulating lipids. In this work, the effect of the pesticide fenitrothion (FS) on the ability of VHDL-apoproteins to uptake different lipids was investigated. For this, VHDL was delipidated using Triton X-100 and recombined with different radiolabeled lipids in the presence or the absence of FS. The oligomeric structural integrity was maintained after delipidation as shown by non-denaturating PAGE. In the presence of the insecticide, palmitic acid uptake decreased by 28.2 and 62.4% after treating the apolipoprotein with 10 and 20 ppm FS, respectively. Decreases in the uptake of cholesterol, triolein, and phosphatidylcholine caused by FS were 29, 23, and 31% using 10 ppm, and 40, 44, and 29% using 20 ppm FS, respectively. Fluorescence measurements with the hydrophobic probes diphenylhexatriene (DPH) and diphenylhexatrienyl-propionic acid (DPH-PA) indicate that FS induces a red shift, decreases the intensity and increases the anisotropy of the emission of these probes in the VHDL. These results indicate that insecticide binding to the lipoprotein enhances the environment polarity and restricts the mobility of these probes at their binding site. These changes at the hydrophobic VHDL binding sites could lead to the decreased affinity for lipids and hydrophobic ligands. It is inferred that FS could alter the normal lipid exchange between this lipoprotein and tissues.     

Contamination of fresh and ensiled maize by multiple penicillium mycotoxins

Toxins produced by Penicillium species are reported in maize silage and have been associated with health problems in cattle. Our objectives were to evaluate the prevalence and dynamics of patulin (PAT), mycophenolic acid (MPA), cyclopiazonic acid (CPA), and roquefortine C (ROC) in fresh and ensiled maize. To achieve these objectives we developed a high-performance liquid chromatography method coupled with mass spectrometry to detect all four toxins simultaneously in silage. In addition we collected weather data, information on agronomic practices, and silage fermentation characteristics for each study site. Silage was collected at harvest and after ensiling in 2001 and 2002 from 30 Pennsylvania dairies. The average concentration of toxins (range in parentheses) was: PAT 0.08 microg/g (0.01 to 1.21), MPA 0.16 microg/g (0.02 to 1.30), CPA 0.12 microg/g (0.02 to 1.43), and ROC 0.38 microg/g (0.01 to 5.71). ROC was the most frequently detected toxin (60%), followed by MPA (42%), CPA (37%), and PAT (23%). Of 120 samples tested, 15% contained no detectible levels of toxin, 25% were contaminated with one toxin, 32% with two, 18% with three, and 10% with all four toxins. All four mycotoxins were found in freshly harvested material, contradicting the belief that Penicillium toxin formation occurs exclusively during storage. We observed that weather conditions during specific growth stages of the crop affected the final concentration of toxins in freshly harvested maize. In ensiled material, PAT levels were affected by concentrations of propionic and isobutyric acids. Based on our data, Penicillium mycotoxins can form while the crop is in the field and after ensiling, suggesting that preventative measures should begin prior to ensiling.     

不同种子处理对苗期小麦草地贪夜蛾的室内防治效果

草地贪夜蛾是入侵我国的重大农业害虫, 其寄主植物范围广, 对我国粮食生产安全构成重大威胁?本研究通过室内盆栽接虫试验, 研究不同种衣剂包衣对苗期小麦草地贪夜蛾的防治效果?结果表明, 4种种衣剂处理均能显著提高小麦出苗率, 其中, 480 g/L 四唑虫酰胺种子处理悬浮剂10 mL/kg处理, 小麦出苗率最高, 达到97.78%, 与对照相比增加了21.38%?40%溴酰·噻虫嗪种子处理悬浮剂的保叶效果和防虫效果均表现良好, 其中4.5 mL/kg种子包衣对小麦齐苗后7?14 d和21 d接虫处理的保叶效果分别为76.12%?69.84%和70.45%, 而且, 接虫后14 d全株调查时未见活虫, 防虫效果达到100%?随着接虫时间的推迟, 含有双酰胺类药剂成分的各种衣剂处理对草地贪夜蛾为害麦苗的保叶效果有所下降, 但均显著好于600 g/L吡虫啉种子处理悬浮剂?     

Response by encapsulation of four mealybug species (homoptera: pseudococcidae) to parasitization byAnagyrus pseudococci

The frequency of encapsulation of eggs ofAnagyrus pseudococci (Girault) (Hymenoptera: Encyrtidae) by four mealybug species:Planococcus citri (Risso),PL vovae (Nasonov),Pl. ficus (Signoret) andPseudococcus cryptus Hempel (=citriculus Green), was studied under controlled laboratory conditions. The aggregate percentage of encapsulated eggs (AE) and the percentage of efficient encapsulation (EE) (= percent parasitized mealybugs wherein encapsulation prevented the development of all parasitoid larvae) byPl. citri andPl. vovae did not differ significantly (39.0%vs 38.2% AE and 15.4%vs 17.6% EE, respectively), but was significantly higher than inPs. cryptus (16.2% AE and 5.4% EE). Encapsulation byPl. vovae was significantly higher than byPl. ficus (38.2%vs 20.1% AE and 17.6% vs 7.7% EE, respectively). Neither the host plant nor the rearing temperature significantly affected the incidence of parasitoid encapsulation. It is suggested thatA. pseudococci displays a relatively low physiological adaptation toPl. citri; thus, in a citrus grove, for example,ca 40% of the parasitoid eggs might be lost due to encapsulation. The question of a possible association between encapsulation and host—parasitoid relationships among the mealybugs studied andA. pseudococci, is discussed.     

Detection of Dickeya spp. latent infection in potato seed tubers using PCR or ELISA and correlation with disease incidence in commercial field crops under hot‐climate conditions

Over a 5‐year period (2006–2010), 277 certified, visually healthy potato seed lots, imported from Europe to Israel for commercial use, were tested for Dickeya spp. latent infection by PCR analysis (277 seed lots) and ELISA (154 seed lots). Seeds from these lots were grown in commercial potato fields which were inspected twice a season by Plant Protection and Inspection Services (PPIS). Stem samples were tested for the presence of Dickeya spp. by PCR analysis. PCR and ELISA results from seed lot testing correlated with disease expression in 74 and 83·8% of the cases, respectively. Positive laboratory results with no disease symptoms in the field (‘+lab/?field’ results) comprised 24·7 and 9·7% of the PCR and ELISA analyses, respectively, whereas negative laboratory results with disease symptoms in the field results (‘?lab/+field’) were obtained in 1·3 and 6·5%, of cases respectively. Maximum disease incidence, as well as the number of cultivars expressing disease symptoms, increased over the years of this study, indicating an increase in the prevalence of the disease. Severe disease incidence was observed on cvs Dita, Rodeo, Desiree, Mondial, Tomensa and Jelly. Of the 55 imported seed lots from which disease was recorded in the field, 49 originated from the Netherlands, four from Germany and two from France. None originated from Scotland.     

Influence of some hardwood barks as soil amendments onRotylenchulus reniformis reproduction and growth response of sunflower

Four hardwood barks (HWB) i. e.Acacia arabica (AA),Ficus sycomorus (FS),Morus alba (MA) andZiziphus spinachristi (ZS) were tried as soil amendments at 0.5, 1.0 and 1.5% rates w/w for control ofRotylenchulus reniformis and improvement of cv. Giza 1 sunflower growth under greenhouse conditions. All HWB with various concentrations significantly (P≤0.01) reduced numbers of larvae in soil, both females and eggmasses on roots, total final nematode population as well as the nematode build-up as compared to control. 1.5% rate of ZS, AA and MA barks were most effective in reducing numbers of larvae in soil, total final nematode population and the nematode build-up. Also, 1.5% rate of each of FS and AA barks were most effective in reducing numbers of females or eggmasses, respectively. On the other hand, the least reduction in the previous nematode stages and rate of build-up was observed with 0.5% dose of FS bark. Shoot weights were increased significantly with both of 1.0% and 1.5% doses of each of FS and ZS barks and only with 1.5% dose of MA bark. Both shoot lengths and root weights increased significantly with 1.5% dose of all HWB or with 1.0% dose of each of AA and ZS barks as compared to control. No significant increase in root lengths was observed. Generally, there were positive significant correlations between doses of HWB, each of the reductions in the previous nematode stages and increases in sunflower growth criteria.     

吡唑醚菌酯在小麦不同生育期病害防治中的应用

为探讨吡唑醚菌酯对小麦不同生育期病害的防治效果,采用菌丝生长速率法,测定了吡唑醚菌酯对小麦纹枯病菌Rhizoctonia cerealis、根腐病菌Bipolaris sorokiniana、全蚀病菌Gaeumannomyces tritici及赤霉病菌Gibberella zeae的室内抑制活性;通过种子发芽盒试验,测定了吡唑醚菌酯不同药种比包衣处理对小麦种子发芽的影响;采用菌土混合法,测定了5%吡唑醚菌酯种子处理悬浮剂(FS)对小麦纹枯病的盆栽防效;同时测定了5%吡唑醚菌酯悬浮剂(SC)对小麦白粉病、锈病及赤霉病的田间防效。结果表明：吡唑醚菌酯对小麦纹枯病菌、根腐病菌、全蚀病菌和赤霉病菌的EC₅₀值分别为0.404、5.862、0.193和1.372 mg/L。25℃条件下,5%吡唑醚菌酯FS不同药种比对济麦22鲜重及干重均有一定的促进作用;10℃下,对小麦种子发芽势、发芽率、发芽指数及活力指数均显示出一定的促进作用。5%吡唑醚菌酯FS苗后20 d对小麦纹枯病的防效在74%以上,药种比1∶50时防效达99.02%;5%吡唑醚菌酯SC按3000 mL/hm     

Laboratory diagnosis of acute toxoplasmosis by immunosorbent agglutination assay (IgM ISA)

A group of 401 patients suspected for toxoplasmosis was examined by the indirect immunofluorescent antibody test (IFAT). All patients positive in IFAT (176) were examined by the immunosorbent agglutination assay (IgM ISA). In the IgM ISA 154 of them were negative, 10 temporarily and 12 high-positive. Some of high-positive patients were examined repeatedly; decrease of high levels of specific IgM antibodies occurred 2-9 months after the first examination. For the IgM ISA antigen prepared from peritoneal exudate of experimentally infected mice was used. The antigen was stable at 4 degrees C or in liquid nitrogen at least 1 year. The IgM ISA combined with IFAT and IgM IFAT was proved satisfactory for the diagnosis of acquired acute toxoplasmosis and can be recommended for laboratories with lower capacity.     

Protective effects of garlic (Allium sativum) extract upon lindane-induced oxidative stress and related damages in testes and brain of male rats

The purpose of this study, carried out on male Wistar rats, was to evaluate the beneficial effects of garlic (Allium sativum) extract injections upon lindane-induced damages in testes, brain and thyroid function. Under our experimental conditions, lindane poisoning (in drinking water for 30 days, supplying about 50 mg/kg body weight per day) resulted in a decreased weight of testes, epididymides, prostate gland and seminal vesicles (−52%, −42%, −50% and −5%, respectively), a decrease of spermatozoa count and motility (−56%, −37%, respectively), an increased level of free thyroxin (+84%) and decreased levels of TSH and FSH in serum (−74%, −77%, respectively). In addition, lindane treatment triggered an oxidative stress in testes and brain as revealed by an increased level of lipids peroxidation (TBARS) (+96%,+92%), an increase of superoxide-dismutase activity in testes (+69%) and a decrease of glutathione-peroxidase and catalase activities in testes and brain (−52%, −34% and −49%, −45%, respectively). These lindane-induced changes were almost reversed to normal in animals injected with a garlic extract (an amount corresponding to 300 mg fresh garlic/kg/day), what confirms a beneficial effect of this vegetal source of anti-oxidants.     

阿拉善荒漠草地8种牧草营养物质季节动态及营养均衡价评价

探讨了阿拉善荒漠草地珍珠柴(Salsola passerina)、霸王(Zygophyllum xanthoxylon)、红砂(Reaumuria soon-gorica)、绵刺(Potaninia mongolica)、梭梭(Haloxylon ammodendron)、盐爪爪(Kalidium foliatum)、沙鞭(Psammochloavillosa)和牛心朴子(Cynanchum komarovii)8种牧草营养物质含量的季节动态,并以粗蛋白质对其营养均衡价进行了比较。结果表明:8种牧草的粗蛋白质、粗脂肪、无氮浸出物、钙含量和钙磷比随着牧草的生长期呈先增加后降低的趋势,粗蛋白质含量6月最高,为7.86%~19.18%,1月最低,为5.25%~9.24%;粗脂肪、无氮浸出物、钙含量及钙磷比分别为0.81%~9.63%,26.19%~52.58%,0.12%~1.93%和0.86%~16.00%。粗纤维含量随植物生长呈降低趋势,且8种牧草的含量差异性较大,范围为9.56%~43.01%;粗灰分含量随生长期没有明显的季节动态规律;磷含量随牧草的生长而降低,范围0.04%~0.20%。牧草营养均衡价的评价表明:8种牧草营养均衡价(NB)依次为:梭梭绵刺珍珠柴霸王红砂盐爪爪牛心朴子沙鞭。     

Entamoeba histolytica--the virulence of imported strains

We tested the virulence of 15 strains of Entamoeba histolytica, imported to Czechoslovakia, by intracaecal inoculation of laboratory rats. According to the scoring system of Neal, none of the 15 strains possessed the virulence index greater than 2. This indicates that all the organisms tested should be classified as avirulent. However, it should be noted that all the strains produced infection of the caecum and thus should be considered infective for rat. For 7 strains, isoenzyme patterns were determined for PGM, HK and ME. One imported strain, obtained from student from Congo, demonstrated isoenzyme pattern for PGM and HK indicated that the strain was virulent. This organisms had the index of virulence 1.8 (avirulent) in animal experiment; it was isolated from cysts of clinically asymptomatic patient. Examination of the rectal mucosa of the donor of the strain indicated typical chronic catarrhal proctitis of mild degree. Examination of the patient's serum demonstrated the presence of anti E. histolytica antibodies by CIEP, while the ELISA test was negative. Twenty-one cyst carriers were examined by rectoscopy. Pathologic changes were observed in 20 of these, as follows: altered vascular structure (13X), roughened mucosa (12X), mucosal reddening (10X), decreased glistening (7X), mucus in mucosa (5X), inflammatory pseudopolypes (2X), ulcers (2X), enanthema (1X). Histological biopsies were obtained in 15 cases. One was considered normal. Remaining 14 biopsies exhibited following morphological changes: increased mucus secretion (8X), edema (7X), lymphocytic and plasmocytic infiltration (6X), lymphocytic and plasmocytic infiltration in addition to the presence of eosinophilic granulocytes (6X), presence of mucophages (5X), haemorrhages (4X), increased vascularity (3X), lymphocytic and plasmocytic infiltration with presence of extremely abundant eosinophilic granulocytes (1X), erosive-ulcerative changes of mucosa (1X). The changes observed indicated chronic catarrhal proctitis with expression to greater or less degree of signs of chronic catarrhal inflammation.     

Biological activity of neem seed kernel extracts and synthetic azadirachtin against larvae of Plutella xylostella L

The activity of two neem extracts, AZT and NEEM-AZAL (containing 30 and 3 mg azadirachtin ml^?1 respectively) and synthetic azadirachtin (AZ) against second-instar larvae (L2) of Plutella xylostella L. was examined using leafdip bioassays. On Chinese cabbage, AZ was significantly (P <0.05) less toxic (3 to 4-fold; LC₅₀ 0.54 μg AZ ml^?1) than either neem extract against a laboratory strain of P. xylostella (FS). The LC₅₀ values for AZT against the FS and another laboratory strain (Wellcome) were not significantly different on Chinese cabbage. The activity of AZT against the FS and Wellcome strains was similar on Chinese cabbage and Brussels sprout. AZT was significantly less toxic (3-fold) on Brussels sprout against an acylurea-resistant field strain (Sawi) when compared with the FS strain on Chinese cabbage. Larval mortality (at day 13) was found to increase with increasing exposure time of P. xylostella (FS) larvae to AZT-treated Chinese cabbage, although there was little difference in mortality between 48 and 120 h exposure. When AZT, NEEM-AZAL and AZ were applied at a dose (1 μg AZ ml^?1) which gave end-point mortalities between 50 and 90% (at day 13), all treatments delayed the development of a proportion of surviving larvae but no morphogenetic abnormalities were observed in larvae which reached pupation. Evidence for antifeedant (reduced weight gain) and repellant effects (choicechamber) for AZT were observed with L2 P. xylostella (Wellcome) on Chinese cabbage. AZT was also shown to have ovicidal activity against P. xylostella (Wellcome) at relatively high dose ranges (10-1000 μg AZ ml^?1) as well as some contact activity (FS strain) in topical bioassays. In residual bioassays on glass with adults of the hymenopteran endo-larval parasitoid of P. xylostella, Diadegma semiclausum (Ichneumonidae), AZT showed little or no activity at rates up to 1000 μg AZ ml^?1. In medium-volume (MV, 200 litre ha^?1) and ultra-low-volume (c. 1 litre ha^?1) spray bioassays on Brussels sprout, AZT gave 16-92% and 88-100% mortality respectively (Wellcome strain) at rates approximating to 1-20 g AZ ha^?1. The residual activity of AZT and NEEM-AZAL against P. xylostella (FS) on Brussels sprout (MV spray) was observed to decrease appreciably after three days, the decline in activity being particularly marked for NEEM-AZAL.     

云南、福建、湖南烟区烟草花叶病主要病毒种类检测及黄瓜花叶病毒亚组鉴定

 采用抗原直接包被和双抗体夹心酶联免疫吸附测定法(ELISA)对采自云南、福建、湖南烟区烟草花叶病样品进行了病毒种类检测,利用三抗体夹心ELISA对黄瓜花叶病毒(Cucumber mosaic virus,CMV)的亚组类型进行了鉴定。在云南采集的520个花叶病样品中,烟草花叶病毒(Tobacco mosaic virus,TMV)、CMV和马铃薯Y病毒(Potato virus Y,PVY)总检出率分别为71.74%、55.01%和6.35%;在福建采集的150个花叶病样品中,TMV、CMV和PVY的总检出率分别为94%、24.66%和8.00%;在湖南采集的74个花叶病样品中,TMV、CMV和PVY的总检出率分别为58.11%、51.35%和2.70%。部分样品为2种以上病毒复合侵染。云南、福建和湖南采集的64个CMV阳性样品中,属亚组Ⅰ的样品为57个,占89.1%;属亚组Ⅱ的样品为10个,占15.6%;其中3个样品为亚组Ⅰ和亚组Ⅱ的复合侵染。     

不同深松方式对玉米产量和水分利用效率的影响

由于我国北方地区长期采用小型机具进行耕作,导致农田耕层变浅、犁底层向上移动,土壤蓄水能力下降。为了明确不同深松方法对作物产量和水分利用效率的影响,提高作物抗旱能力和生产能力,本研究通过3 a定位试验,以春季旋耕为对照（CK）,研究了秋季全方位深松（BS）、秋季连年垄台深松（RS）、初夏连年垄沟中耕深松（FS）和秋夏年际交替间隔深松（AS）4种深松耕作方式的蓄水和增产效应。试验研究结果表明,可以将不同耕作处理土壤容重特征表述为：CK为上虚下实型、BS为均匀疏松型、RS为垄虚沟实型、FS为垄实沟虚型(相对RS)、AS为年际疏松交替型。BS、AS、FS和RS不同年份土壤平均贮水量较CK增幅的变化范围分别是10.9～23.2 mm、10.9～17.2 mm、9.0～15.7 mm和6.0～8.2 mm,尽管AS的容重在年际间存在更替变化,但对年际间土壤平均贮水量影响较小。总体上BS和AS土壤贮水量高于CK和RS,提高10.9～23.2 mm,能够为不同降水年型下玉米稳产提供保障。尤其相对于其他3种深松方式,AS处理3 a研究数据玉米持续保持着高生产能力和水分利用效率,较CK产量提高17.22%～28.65%,水分利用效率提高0.27～0.73 kg·m^-3; 2013年较BS的产量和水分利用效率差异不显著,其他两年分别提高1.00%～5.92%,0.06～0.20 kg·m^-3;较FS产量提高5.59%～13.50%,2014年水分利用效率差异不显著,其他两年提高0.20～0.43 kg·m^-3,因此AS是较为适宜的深松方式。     

广东水稻白叶枯病菌遗传多样性和小种分化研究

 通过IS-PCR和rep-PCR指纹技术,分析了广东水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae)群体遗传多样性。用2对特异性引物J3和ERIC对114个菌株基因组DNA进行了PCR扩增,分别呈现89和40种谱型,以彼此间的带位相似率达70%为界,J3扩增的谱型被分为11簇,ERIC的谱型被分为8簇。J3的簇1包含89个菌株,占总数的78.07%,ERIC的簇1包含52个菌株,占总数的45.61%,均为优势簇群。群体遗传多样性值J3为0.8919,ERIC为0.8278。上述结果表明,广东水稻白叶枯病菌的遗传多样性较高。全部参试菌株接种于含有不同抗性基因近等基因系及高感品种金刚30共6个鉴别品种,被划分为6个小种(X-gd1,X-gd2,X-gd3,X-gd4,X-gd5和X-gd6),X-gd4出现频率最高,为广东省的优势小种。