硅对黄瓜霜霉病抑制效果和抗性相关酶活性的影响

在营养液中加入不同浓度硅且接种黄瓜霜霉病菌后,通过调查其病情指数和检测黄瓜叶片内硅元素含量及过氧化物酶(guaiacol-peroxidase,POD)、多酚氧化酶(polyphenol oxidase,PPO)、苯丙氨酸解氨酶(phenylalanine ammonia-lysae,PAL)、β-1,3葡聚糖酶(β-1,3-glucanase)、超氧化物歧化酶(superoxidedismutase,SOD)5种抗霜霉病相关酶活性,探讨硅抑制黄瓜霜霉病的生理生化机制。结果表明,营养液中硅浓度为100mg/L的处理,黄瓜霜霉病病情指数为21.3,防治效果达到62.8%;营养液中硅浓度与黄瓜叶片内硅元素含量呈正相关,200mg/L处理叶片内硅元素含量最高,且7天后达到2.98mg/g;加硅处理接种黄瓜霜霉病菌后,黄瓜叶片抗病相关酶活性变化明显且差异达显著水平,其中硅浓度为100～200mg/L时上述5种酶活性最高。     

干旱胁迫下硫对玉米叶绿素及MDA含量的影响

以高水肥型玉米品种为供试作物，选用4种不同硫浓度的Hoagland营养液进行培养试验，以PEG-6000模拟干旱胁迫，测定了三叶期后玉米功能叶片中叶绿素、丙二醛MDA含量的交化。结果表明：增加硫营养供应对提高叶片中叶绿素含量具有非常重要的作用。随着营养液中硫浓度的增加，功能叶片中叶绿素含量有明显的提高，并且硫营养对叶绿素含量的影响可能存在一个浓度阈值；干旱可明显导致叶绿素含量的降低，但随着营养液中硫浓度的增加，对功能叶片中叶绿素含量的降低有明显的抑制作用；在复水过程中硫营养表现出明显的效应．其叶绿素含量会得到不同程度的恢复；干旱胁迫可导致叶片中MDA含量增加．但有硫处理的玉米叶片MDA含量显著低于无硫处理，表明硫营养能减轻干旱造成的膜伤害。     

氮钾水平与全多酚对柠檬流胶病抗性的影响

Ｎ、Ｋ水平与柠檬抵御流胶病病原菌侵染能力有密切关系。在营养液中Ｎ浓度大于２４０ｍｇ／ｋｇ，树体对流胶病抵御能力降低；在Ｋ浓度小于２２０ｍｇ／ｋｇ范围内，提高Ｋ水平能明显提高树体抗流胶病的能力。叶片中全多酚的含量与树体抗流胶病能力强弱有关，在营养液中Ｎ浓度为２４０ｍｇ／ｋｇ，Ｋ浓度为２２０ｍｇ／ｋｇ时，叶片全多酚含量为９．１７ｍｇ／ｇ，树体具有较强的抗流胶病能力。     

Pb和NaCl胁迫对黄瓜幼苗生理生化特性的影响

为了揭示Pb和NaCl单一及复合胁迫对黄瓜幼苗的伤害机理,采用砂培法,以不添加Pb和NaCl为对照,研究了不同浓度Pb(0.5和1.5 mmol/L)、NaCl(50和100 mmol/L)及其复合胁迫对黄瓜幼苗生理生化特性的影响。结果表明,随着Pb、NaCl处理浓度升高,黄瓜叶片的叶绿素a、叶绿素b和叶绿素a+b含量均显著下降;相对于对照,各处理黄瓜叶片的相对电导率、丙二醛含量明显上升,且100 mmol/L NaCl胁迫下黄瓜叶片的相对电导率和丙二醛含量均高于1.5 mmol/L Pb胁迫。不同处理下的可溶性糖含量、脯氨酸含量、SOD和POD活性均高于对照,且复合处理下的含量高于单一因子处理。NaCl对黄瓜叶片细胞膜的破坏作用强于Pb,Pb、NaCl复合胁迫的毒性效应强于单一胁迫,表现为协同作用。     

6.9%精噁唑禾草灵水乳剂(骠马)对核桃苗、枣树生理生化影响的研究

6．9％精嚼唑禾草灵水乳剂（骠马）能有效的防除小麦田里的阔叶杂草，但在枣麦、核桃麦间作田里能否安全应用，值得探讨。本文通过对6．9％骠马水乳剂在3种浓度处理下对核桃苗及枣树叶片内叶绿素含量、丙二醛含量及生长量等的测定．研究了骠马对核桃苗及枣树生长发育的影响。试验结果表明：在核桃苗圃地或核桃一小麦间作地使用骠马，应于萌芽前后5d施用，但浓度不应高于4mL／L；在枣粮间作地，骠马在1、2mL／L浓度下方可使用。     

ALA和CaCl2处理对黄瓜植株初花期、结果期盐胁迫的缓解效应

试验以津春4号黄瓜(Cucumis sativus L.)为材料,研究了ALA(5-aminole-vulinic acid)和CaCl2两种外源物质对150 mmol/L和250 mmol/L NaCl胁迫下黄瓜植株在初花期和结果期生理生化指标的影响。结果表明,ALA的作用效果较CaCl2显著,可显著提高黄瓜叶片中可溶性蛋白含量、叶绿素b/a值,降低细胞膜透性,提高根系活力,抑制MDA产生,增加黄瓜植株对盐胁迫的抵抗能力,显著提高盐胁迫下黄瓜产量,与盐胁迫下的对照相比小区产量分别提高24.9%和52.3%。     

唑胺菌酯对黄瓜和番茄生理指标及保护酶活性的影响

采用室内盆栽试验,系统地研究了杀菌剂唑胺菌酯(SYP-4155)对黄瓜和番茄生长发育过程中生理指标及保护酶活性的影响.结果表明,与空白对照相比,唑胺菌酯明显提高了黄瓜和番茄叶片中叶绿素含量,且浓度为300mg/L时影响最大,在一定范围内,叶绿素含量与该药剂的浓度呈正相关,可溶性糖含量和蛋白质含量则变化不大;施用不同浓度的唑胺菌酯后,叶片中保护酶(过氧化物酶POD、多酚氧化酶PPO、过氧化氢酶CAT、超氧化物歧化酶SOD)的活性在一定时间内均比对照高,浓度为300mG/L时黄瓜中4种酶的活性分别较对照高34.67%、34.78%、36.36%和11.94%,且浓度越高,酶活性的变化越大.     

黑麦草幼苗对NaHCO3胁迫的生理响应

采用营养液砂培方法,研究了不同浓度NaHCO3(0、50、100、150 mmol/L和200 mmol/L)胁迫对黑麦草幼苗生长、活性氧代谢和渗透溶质积累的影响。结果表明:(1)随着NaHCO3浓度增加,黑麦草幼苗鲜、干重呈降低趋势,叶片超氧阴离子(O2.)、过氧化氢(H2O2)、丙二醛(MDA)和Na+含量不断升高,过氧化氢酶(CAT)、过氧化物酶(POD)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、K+含量及K+/Na+持续下降,超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性呈先升后降变化,液泡膜H+-ATPase和H+-PPase活性在NaHCO3浓度为50～150 mmol/L时高于对照,NaHCO3浓度为200 mmol/L时低于对照。(2)碱胁迫降低了幼苗叶片中可溶性蛋白质和游离氨基酸的含量,提高了可溶性糖和脯氨酸的含量。表明活性氧代谢和Na+、K+平衡失调及积累有机溶质进行渗透调节需更多能耗等可能是碱胁迫下黑麦草幼苗生长受抑的重要因素。     

钙对NaCl 胁迫下玉米幼苗保护酶活性等生理特性的影响

采用水培法研究了不同浓度钙对盐胁迫下玉米幼苗生长、叶绿素含量、游离氨基酸含量及保护酶活性等生理特性的影响。结果表明适量的Ca2 (4 mmol/L)供应能有效促进玉米生长,抑制叶绿素含量降低,降低细胞膜透性,提高玉米叶片和根系中的SOD和POD活性,随着Ca2 浓度增加根系中CAT活性增加,叶片CAT活性有所下降。增加Ca2 浓度,根系中游离氨基酸含量和可溶性蛋白含量呈现出先升高(2~4 mmol/L)后降低(6mmol/L)趋势,叶片中可溶性蛋白含量随Ca2 浓度增加而降低。表明适量的Ca2 供应可提高玉米幼苗耐盐性。     

作物秸秆对黄瓜衰老中根系活力和叶片氮代谢的影响

以‘津优4号’黄瓜为试验材料,研究施用不同作物秸秆对衰老过程中黄瓜根系活力和叶片氮代谢关键酶、叶片氮素含量及可溶性蛋白含量等影响。结果表明,与对照相比,作物秸秆还田不仅显著提高了黄瓜的根系活力、叶绿素含量和叶片氮代谢关键酶硝酸还原酶、谷氨酰胺合成酶、谷氨酸合成酶的活性,降低了谷氨酸脱氢酶活性,而且还降低了叶片铵态氮的含量（15．6μg·g－1）,提高了叶片硝态氮、可溶性蛋白及游离氨基酸的含量,有效地保持较高的氮代谢水平,延缓了黄瓜的衰老。其中施用玉米秸秆效果最好,黄瓜的根系活力、硝酸还原酶活性、可溶性蛋白含量分别比对照提高了23．4％、33．3％、18．7％,其次为花生秸秆,硝酸还原酶活性比对照提高了10．8％,施用稻壳效果不明显。     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Effect of botanical insecticides and bacterial toxins on the gut enzyme of the rice leaffolderCnaphalocrocis medinalis

The effect of botanical insecticides and bacterial toxins on gut enzyme activity of larvae of the rice leaffolderCnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae) was investigated. Gut enzyme activities were affected by botanical insecticides and bacterial toxin individually and in combination. When fed a diet of rice leaves treated with botanical insecticides and bacterial toxins, in bioassays the activities of gut tissue enzymes — acid phosphatases (ACP), alkaline phosphatases (ALP) and adenosine triphosphatases (ATPase) — of rice leaffolder larvae were affected. When combined, the effect was more severe at a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP and ATPase activities. The combination ofBacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear dose-response relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic pesticides in controlling RLF. http://www.phytoparasitica.org posting Sept. 28, 2004.