盐碱胁迫对油菜种子萌发和根尖细胞有丝分裂的影响

以冬油菜品种“陇油6号”为材料,通过中性盐NaCl∶Na₂SO₄(9 mol∶1 mol)混合胁迫(浓度为40、80、120、160、200 mmol·L^-1和240 mmol·L^-1,Na⁺浓度依次为44、88、132、176、220 mmol·L^-1和264 mmol·L^-1)和碱性盐NaHCO₃∶Na₂CO₃ (9 mol∶1 mol)混合胁迫(浓度为10、20、30、40、50 mmol·L^-1和60 mmol·L^-1,Na⁺浓度依次为11、22、33、44、55 mmol·L^-1和66 mmol·L^-1)处理油菜种子和幼苗,研究不同盐、碱胁迫下油菜种子萌发特性并观察根尖细胞有丝分裂的形态变化。结果表明：对“陇油6号”种子萌发和幼苗生长无害的最大混合盐浓度为160 mmol·L^-(pH=6.67,Na⁺=176 mmol·L^-1),最大混合碱浓度为50 mmol·L^-1(pH=9.29,Na ⁺=55 mmol·L^-1);随着盐、碱胁迫浓度增大,“陇油6号”幼苗根尖细胞有丝分裂指数逐渐 降低,细胞微核率和染色体畸变率先上升后下降,碱性盐溶液胁迫下降幅度明显大于中性盐溶液胁迫;在同一盐、碱胁迫浓度时,处理时间越长,根尖细胞有丝分裂指数越低,染色体畸变率和微核率越高。这表明盐、碱胁迫对“陇油6号”种子萌发和幼苗生长是两种不同的胁迫,且碱性盐胁迫强于中性盐。     

钙对低温胁迫下玉米幼苗氧化损伤的保护作用

采用室内盆栽试验,利用不同浓度的CaCl₂（0、5、10、15、20 mmol·L^-1）处理低温胁迫下的玉米幼苗,研究了钙对玉米幼苗抗冷性的作用。结果表明：与对照相比,低温处理明显抑制了玉米幼苗的生长,减缓了可溶性蛋白和可溶性糖含量的积累,抗氧化酶活性下降,脯氨酸含量减少,丙二醛（MDA）含量增加,质膜透性增大。适宜浓度的钙（5～10 mmol·L^-1）能减缓低温胁迫下玉米幼苗质膜相对透性和丙二醛（MDA）含量的增加,促进脯氨酸(Pro)、可溶性糖和可溶性蛋白的积累,提高超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）活性,其中10 mmol·L^-1 Ca²⁺处理的效果最为明显。     

外源H2S对渗透胁迫下裸燕麦种子萌发和幼苗生长的影响

为探讨新型气体信号硫化氢(H₂2S)对渗透胁迫下作物种子萌发和幼苗生长的影响，以裸燕麦(Avena nude)品种‘定莜9号’种子为材料，采用H₂2S供体硫氢化钠(NaHS)浸种浓度和聚乙二醇(PEG-6000)模拟渗透胁迫两因素试验，其中NaHS浓度设0、0. 2、1. 0 mmol·L^-1和5. 0 mmol·L^-14个水平，PEG浓度设0、119、149、178 g·L^-1和202 g·L^-15个水平，进行完全组合设计，共20个处理，测定不同处理裸燕麦种子萌发参数(发芽势、发芽率、发芽指数、活力指数、平均发芽时间和贮藏物质转运率)和幼苗生长参数(胚根长、胚芽长和幼苗干重)，运用隶属函数分析方法对不同处理种子的耐渗透能力进行综合评价。结果表明：（1）NaHS浓度和PEG浓度对各萌发参数和幼苗生长参数均有显著影响；两者的交互作用对发芽指数、活力指数、平均发芽时间和胚根长影响显著。（2）在同一NaHS浓度下，随着PEG浓度提高，各萌发参数和幼苗生长参数均显著下降，而平均发芽时间呈增加趋势。（3）在相同PEG浓度下，0.2 mmol·L^-1NaHS浸种对各萌发参数和幼苗生长参数均无显著影响；1.0 mmol·L^-1NaHS浸种提高了发芽指数、活力指数、贮藏物质转运率、胚根长、胚芽长和幼苗干重，降低了平均发芽时间；5.0 mmol·L^-1NaHS浸种提高了平均发芽时间，而其余各萌发参数和幼苗生长参数均呈下降趋势。（4）利用隶属函数综合分析得知，用1.0 mmol·L^-1NaHS浸种可提高PEG渗透胁迫下的综合评价D值，而5.0 mmol·L^-1NaHS浸种处理的D值显著下降。由此表明，适宜浓度NaHS (1.0 mmol·L^-1)浸种能够促进渗透胁迫下裸燕麦的种子萌发和幼苗生长。     

外源水杨酸对野生龙葵幼苗干旱胁迫的缓解效应

利用20%的PEG6000模拟干旱胁迫,同时用不同浓度（0、0.5、1.0、1.5、2.0 mmol·L^-1）的水杨酸(SA)喷施幼苗,研究了不同浓度水杨酸处理对干旱胁迫下野生龙葵幼苗生长的影响。结果表明：干旱胁迫下,龙葵幼苗植株变矮、鲜重降低、根长缩短,叶绿素和可溶性蛋白含量减少,抗氧化酶活性、游离脯氨酸和丙二醛含量增加;经SA处理干旱胁迫下龙葵幼苗株高、根长和鲜重都有明显增加,特别是1.5 mmol·L^-1 SA处理组分别增加20.8%、28.0%和29.7%,1.5 mmol·L^-1 SA处理组龙葵幼苗叶绿素含量提高31.9%、脯氨酸含量提高65.4%,可溶性蛋白含量提高42.8%,超氧化物歧化酶（SOD）、过氧化物酶（POD）与过氧化氢酶（CAT）活性达到最高,与对照相比分别增加了30.2%、87.8%和50.3%;SA处理使丙二醛（MDA）含量降低了37.8%。综合来看,适当浓度的SA可以缓解干旱对龙葵幼苗造成的伤害,并以1.5 mmol·L^-1外源SA缓解效果最好。     

外源SA和CaCl2对低温胁迫下糯玉米幼苗生理特性的影响

早春糯玉米易遭受低温冷害的影响，为探讨外源物对糯玉米幼苗低温胁迫的缓解作用，以‘万糯2000’、‘润糯73’为试验材料，分别采用0、25、50、100、150 mg·L^-1水杨酸（SA）和0、40、80、120、160 mmol·L^-1 CaCl₂处理糯玉米幼苗，研究外源SA和CaCl₂对低温胁迫下玉米幼苗生理特性的影响。结果表明：适宜浓度SA、CaCl₂处理下，‘万糯2000’和‘润糯73’幼苗叶片可溶性蛋白、脯氨酸含量分别较各自对照增加42.9%、18.3%和96.1%、16.7%，过氧化氢酶和过氧化物酶活性分别提高231.0%、76.5%和9.5%、13.9%，丙二醛含量分别降低78.7%、67.1%，缓解了低温胁迫对糯玉米幼苗的伤害。‘万糯2000’和‘润糯73’适宜的CaCl₂处理浓度均为40 mmol·L^-1；‘万糯2000’适宜的SA处理浓度为100 mg·L^-1，‘润糯73’适宜的SA处理浓度为50 mg·L^-1。综合比较分析，喷施40 mmol·L^-1 CaCl₂可有效提高糯玉米幼苗的耐低温能力。     

茉莉酸甲酯响应盐碱胁迫下苹果砧木M26的生理机制

为探索外源茉莉酸甲酯（MeJA）处理后苹果砧木对盐碱胁迫的响应特性，以苹果砧木M26为试验材料，设置CK1（清水浇灌)、CK2（盐碱胁迫：200 mmol·L^-1NaCl∶NaHCO₃=1∶1）、T1（盐碱胁迫+0.05 μmol·L^-1MeJA）、T2（盐碱胁迫+0.5 μmol·L^-1MeJA）、T3（盐碱胁迫+5 μmol·L^-1MeJA）、T4（盐碱胁迫+50 μmol·L^-1MeJA）、T5（盐碱胁迫+500 μmol·L^-1MeJA）共7个处理，观察并测定各处理下苹果砧木生长的表型、光合色素以及渗透调节物质含量，并对其进行相关性和主成分分析。结果表明：与CK2相比，喷施MeJA处理幼苗叶片边缘黄化未扩大，叶绿素a（Chl a）含量、叶绿素b（Chl b）含量、叶绿素a+b（Chl a+b）含量、净光合速率（P_n）、可溶性糖（SS）含量、可溶性蛋白（SP）含量、超氧化物歧化酶（SOD）活性、脯氨酸（Pro）含量、过氧化物酶（POD）活性、过氧化氢酶（CAT）活性均有所升高，其中T4升幅最大，各指标平均增幅范围为12.77%~69.80%；喷施MeJA处理的叶片电导率（REC）、超氧阴离子（O^₂）含量、丙二醛（MDA）含量相比CK1有所升高，T1、T2、T3、T5处理各指标升高幅度范围为30.5%~109.2%，其中T4增幅最小，为18.72%~45.02%。相关性分析表明，Chl a与Chl b、Chl a+b含量呈极显著正相关关系，与MDA、O^₂含量及REC呈极显著负相关关系，与SP、H₂O₂含量呈显著负相关关系。对17个指标进行主成分分析，3个主成分累积方差贡献率达到95.25%；依据主成分进行综合排序，外源MeJA对盐碱胁迫下M26幼苗叶片缓解能力表现为T4>T5>T3>T2>T1。综上，在200 mmol·L^-1浓度盐碱胁迫下，施用50 μmol·L^-1的外源茉莉酸甲酯对苹果砧木生理特性的调节效果最佳。     

外源一氧化氮对铅胁迫下玉米幼苗的缓解作用

为探讨Pb胁迫下外源一氧化氮（NO）对玉米幼苗伤害的缓解作用,利用室内盆栽试验研究了外源NO供体硝普钠（SNP）对铅（Pb）处理下玉米（Zea mays）幼苗生长及生理特性的影响。结果表明：与对照相比,1.0 mmol·L^-1 Pb处理明显抑制了玉米幼苗的生长,减缓了玉米幼苗可溶性蛋白和可溶性糖含量的积累,抗氧化酶活性下降,叶绿素含量减少,丙二醛（MDA）含量增加、质膜透性增大;添加0.1 mmol·L^-1的SNP明显缓解了Pb胁迫对玉米幼苗生长的抑制作用,提高Pb胁迫下超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性,增加了幼苗叶绿素和脯氨酸含量,促进了可溶性糖和可溶性蛋白的积累,降低了MDA含 量、细胞质膜的透性。外源NO对Pb胁迫下玉米生长有一定的缓解作用,可以增强玉米幼苗对Pb毒害的抗性。     

亚精胺对渗透胁迫下甜瓜幼苗膜脂过氧化和抗氧化系统的影响

为探讨多胺提高作物抗渗透胁迫的生理机制，以甜瓜品种‘齐甜2号’为材料，采用营养液法培养甜瓜幼苗，以15% PEG-6000模拟渗透胁迫，研究1 mmol·L^-1亚精胺（Spd）对不同渗透胁迫时间下甜瓜幼苗的生长、活性氧代谢、抗氧化酶活性、渗透调节物质和非酶抗氧化剂的影响。结果表明：渗透胁迫后4 d，与胁迫处理相比，1 mmol·L^-1 Spd处理使甜瓜幼苗生物量提高11.34%，根系活力提高24.20%；叶片和根系H₂O₂含量、O^₂产生速率、MDA含量和相对电解质渗透率降低，叶片中分别降低30.72%、29.99%、29.34%和14.62%，根中分别降低29.33%、25.31%、28.23%和20.34%。Spd诱导甜瓜叶片和根系中抗氧化酶活性增加，与胁迫处理相比，叶中SOD、POD、CAT和APX抗氧化酶活性分别提高25.54%、28.70%、27.72%和28.41%，根中分别提高23.35%、27.38%、25.06%和20.34%。与渗透胁迫处理相比，Spd处理在渗透胁迫后16 d甜瓜幼苗叶片脯氨酸、可溶性糖和可溶性蛋白的含量分别增加46.51%、49.72%和40.25%；渗透胁迫后16 d幼苗叶片ASA含量增加62.50%，渗透胁迫后12 d幼苗叶片GSH含量增加37.17%，ASA/DHA和GSH/GSSG分别提高74.46%、60.95%。说明在渗透胁迫下1 mmol·L^-1浓度Spd能够促进甜瓜幼苗生长，稳定生物膜系统，增强甜瓜幼苗抗氧化能力，有效缓解渗透胁迫对甜瓜幼苗伤害的作用。     

壳寡糖对干旱胁迫下信前胡生长及叶片生理特性的影响

以信前胡盆栽幼苗作为研究材料,通过测定信前胡的株高、叶面积、生物量、含水量、根冠比和叶片抗旱相关的生理指标,研究了5、10、15 mg·L^-1和2 mg·L^-1的壳寡糖(Chitooligosaccharide,COS)溶液处理对干旱胁迫下信前胡生长和叶片生理特性的影响。结果表明,不同浓度壳寡糖对干旱胁迫下信前胡生长均有不同程度的促进作用,且随壳寡糖浓度的增加,各生长指标均表现出先增后降的趋势,均有一定的最适浓度。与单纯干旱处理相比,5、10、15 mg·L^-1和20 mg·L^-1壳寡糖处理信前胡的单株叶片数分别提高了32.5%、50.8%、29.3%和6.3%,均达到了显著水平（P<0.05）;10 mg·L^-1和15 mg·L^-1壳寡糖处理信前胡的单株平均叶面积分别提高了27.3%和20.8%,均达到了显著水平（P<0.05）;5、10、15 mg·L^-1壳寡糖处理信前胡的株高分别显著提高了17.4%、31.7%和19.6%。10 mg·L^-1壳寡糖处理信前胡叶片的脯氨酸含量较单纯干旱处理显著提高了11.8%,10 mg·L^-1壳寡糖处理信前胡叶片的H₂O₂含量和MDA含量均较单纯干旱处理显著降低（降幅分别为46.9%和14.4%）。因此,10 mg·L^-1壳寡糖处理可显著缓解信前胡苗期的干旱胁迫（P<0.05）。     

等渗透势盐分和水分胁迫对白刺幼苗生长及离子吸收分配的影响

研究了等渗透势(-0.79、-1.83 MPa)盐分胁迫(NaCl)和水分胁迫(PEG)对西伯利亚白刺(Nitraria sibirica)幼苗生长及不同组织离子吸收分配的差异,探讨白刺抗旱和耐盐的相互关系。结果表明,与对照相比,-1.83 MPa NaCl和PEG处理后白刺幼苗的株高、茎粗、主根长和干物重均极显著(P＜0.01)降低,可溶性糖、脯氨酸和丙 二醛含量均显著(P＜0.05)或极显著(P＜0.01)升高,其中NaCl对幼苗生长的抑制作用显著(P＜0.05)大于PEG处理。不同器官离子含量,NaCl各处理的白刺幼苗Na⁺含量均上升,K⁺含量均先升后降,Ca²⁺、Mg²⁺含量及K⁺/Na⁺、Ca²⁺/Na⁺和Mg²⁺/Na⁺值均下降;PEG各处理的白刺幼苗Na⁺含量均先降后升,K⁺、Ca²⁺、Mg²⁺含量均下降,K⁺/Na⁺、Ca²⁺/Na⁺和Mg²⁺/Na⁺值均先升后降。不同器官离子的变化幅度以根中最大,茎次之,叶中最小。白刺幼苗主要是通过盐离子的区域化分布和调节幼苗体内的离子平衡来抵抗盐害的,通过积累大量有机小分子物质来抵抗旱害的。     

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.