3种盐胁迫对玉米幼苗生长及叶片抗氧化酶和离子累积的影响

选取2个玉米品种(金玉819和金单999),探讨了3种盐胁迫(NaCl、Na_2SO_4和NaNO_3)对玉米幼苗生长、抗氧化酶活性以及叶片中K~+、Na~+、Ca~(2+)累积的影响。结果表明:3种不同类型的盐胁迫均会导致玉米幼苗鲜重下降,地上部鲜重金玉819下降超过28.6%,金单999下降超过18%;盐胁迫下金玉819叶片SOD酶活上升2.1倍以上, POD酶活性最高上升4.5倍,APX最高上升2.1倍,CAT最高上升2.2倍;金单999叶片SOD酶活最高上升2.1倍,APX最高上升1.6倍,CAT最高上升1.9倍。2个基因型玉米胁迫下叶片内Na~+含量上升4.5～6.3倍;NaCl和NaNO_3处理下,K~+/Na~+比对照降低90%～93%,而Na_2SO_4处理下K~+/Na~+下降78%～82%,金玉819和金单999的Ca~(2+)/Na~+比对照分别降低了85%～90%和92%～94%。综合分析表明NO~-_3引起的次生盐害对玉米生产危害较大。与金单999相比,金玉819对盐胁迫更加敏感,相同Na~+浓度处理下,金玉819的鲜重和SOD酶活性下降显著且拥有较低的K~+/Na~+和Ca~(2+)/Na~+值。     

Hygroscopic salts support the stomatal penetration of glyphosate and influence its biological efficacy

The objective of this study was to better understand the role of chaotropic and kosmotropic salts in stomatal uptake, a process that occurs in parallel with cuticular penetration and affects the bioefficacy of glyphosate. In Trial 1, salt solutions of kosmotropic (NH₄)₂SO₄ and chaotropic NaClO₃, with or without the organosilicone surfactant, Break‐Thru® S233 (BT), and with or without glyphosate, were prepared. In Trial 2, sodium salts with a kosmotropic‐to‐chaotropic nature (Na₂SO₄, NaCl, NaNO₃ or NaClO₃) and BT were prepared with or without glyphosate. At very high concentrations, the salts of a kosmotropic nature induced a slight decrease in the surface tension, whereas those of a chaotropic nature triggered a significant decrease in the surface tension. Solution droplets were deposited onto the leaves of Viola arvensis and Chenopodium album. The dried deposits were analyzed with an environmental scanning electron microscope. The salts formed structures linking the exterior to the interior of the stomata in the crystalline ([NH₄]₂SO₄) or amorphous (NaClO₃) form. However, the low surface tension alone did not appear to be the unique driving force for stomatal uptake. With glyphosate, amorphous globular structures of glyphosate salt were formed in the Na₂SO₄ (kosmotropic) solution. Differently, the salts of a rather chaotropic nature (NaNO₃ or NaClO₃) formed a colloidal matrix. In general, salt residues were observed over the periclinal cell walls and inside the stomatal chamber. Neither (NH₄)₂SO₄ nor Na₂SO₄ had a significant impact on glyphosate bioefficacy. However, the chaotropic salt, NaNO₃, enhanced the bioefficacy of glyphosate the most, with a performance that was comparable to that of the solution glyphosate + organosilicone surfactant.     

会宁剖面MIS3阶段黄土元素地球化学特征及气候变化

在会宁剖面元素地球化学数据分析和气候替代指标分析的基础上，重建了会宁地区约20～70 ka的古气候特征和序列。研究表明：Ba、Rb、Sr、Ti、Fe₂O₃、SiO₂、Al₂O₃、MgO、K₂O等在剖面上都有随深度的减小含量随之增加的趋势；CaO、Na₂O等在剖面上有随深度的减小含量随之减小的趋势。MIS3气候略显温湿，可划分为3个阶段：早期(L₁S₁S₂)，55.5～45.9 ka，气候为弱温湿；中期(L₁S₁L₁)，45.9～27.3 ka，气候为干冷；晚期(L₁S₁S₁)，27.3～23.8 ka，气候为温湿；会宁剖面较明显地记录了5次Heinrich事件。     

Synthesis and Structure–Activity Relationships for the Fungicidal Activity of O,O-bisaryl sec-butylphosphonates

Sixteen O,O-bisaryl sec-butylphosphonates have been synthesised by condensing sec-butylphosphonyl dichloride with substituted phenols. The compounds were tested against two phytopathogenic fungi, Rhizoctonia bataticola and Helminthosporium oryzae. The most active compound against R. bataticola is O,O-bis(3-methylphenyl) sec-butylphosphonate (ED₅₀ 29·56 mg litre^-1) and against H. oryzae, O,O-bis(2-chlorophenyl) sec-butylphosphonate and its para-chloro analogue (ED₅₀ 0·14 and 0·13 mg litre^-1 respectively). Quantitative structure–activity relationships on the fungicidal activity have been analysed by means of multiple regression analysis using physicochemical substituent parameters. Electronic parameters viz., σ and F have expressed significant variability in fungitoxicity against both the fungi, viz. R. bataticola and H. oryzae. Hydrophobic and steric parameters are also found to be important in the correlation studies. © 1997 SCI.     

柳枝稷种植年限对土壤盐分离子的影响

为探明能源植物柳枝稷对盐碱土的改良效果,于2014—2015年,在宁夏大学西大滩盐碱地改良试验站田间条件下,设置1、3、5 a3个不同种植年限柳枝稷处理(T1、T3、T5),以附近未种植柳枝稷的盐碱荒地作为对照(CK),研究了不同种植年限柳枝稷对盐碱土盐分离子的影响。结果表明,随着种植年限增加,柳枝稷对土壤盐分离子的作用效果增强,土壤中的Na~+、SO_4~(2-)、Cl~-含量随种植年限增加而降低,在柳枝稷生育末期T5处理与CK相比,Na~+、SO_4~(2-)、Cl~-含量分别下降了52.64%、40.37%和63.68%;土壤中的Ca~(2+)、Mg~(2+)含量与柳枝稷种植年限呈正相关关系,在柳枝稷生育末期T5处理Ca~(2+)、Mg~(2+)含量分别比CK增加了2.22%、48.08%。本试验条件下,柳枝稷种植5年后对土壤Na~+、SO_4~(2-)和Cl~-等盐分离子的降低作用最为明显。     

黄河三角洲滨海棉田土壤盐分特征研究

采用相关分析和主成分分析方法对黄河三角洲棉田试验区土壤盐分特征进行研究,结果表明,试验区土壤为中度盐渍化,且盐分呈现一定的表聚现象;土壤各层盐基离子中,阳离子以Na⁺为主,阴离子以Cl^-为主,这两种离子对棉花生长的毒害作用尤为突出;土壤盐分含量与Na⁺、SO₄^2-、Cl^-、Mg²⁺、Ca²⁺、NO₃^2-、HCO₃^2-离子含量均呈极显著正相关;Na⁺、Cl^- 及SO₄^2-是影响试验区棉田盐渍化的主要特征因子。本研究结果可为黄河三角洲地区盐渍化土地科学管理和农业可持续发展提供理论基础和实践依据。     

The effect of nitrogen on the growth and development of giant witchweed,Striga hermonthica Benth.: effect on cultured germinated seedlings in host absence

For the first time in sterile nutrient media in the absence of the host plant, different forms and rates of nitrogen compounds were screened for their effect onS. hermonthica Benth. shoot development beyond seed germination. There was no shoot formation beyond the inoculation stages whenS. hermonthica germlings were grown in media devoid of nitrogen source. In culture media containing some nitrogen sources, healthy shoots were formed. Increasing concentrations of KNO₃, NaNO₃, Ca(NO₃)₂, Mg(NO₃)₂ and asparagine resulted in a significant increase inS. hermonthica shoot development. Inversely, increasing concentrations of (NH₄)₂SO₄, NH₄H₂PO₄, NH₄Cl and urea led to increasing significant reduction ofS. hermonthica shoot development. The amino acids, glycine and asparagine supported reduced shoot development ofS. hermonthica, indicating that organic nitrogen cannot replace inorganic nitrogen forStriga growth. The ammonium nitrogen compounds, (NH₄)₂SO₄ and NH₄H₂PO₄, suppressed further shoot elongation and total dry weight of 20 and 40 days oldStriga hermonthica plants, in sterile culture media. The organic compounds urea, allylthiourea and thiourea had an effect similar to ammonium compounds. Arginine and glycine on the other hand did not suppress the further development of the parasite. The suppressive effect of nitrogen however, was greater when the parasite was 20 days old than when it was 40 days old. This work provides data to show that some nitrogen compounds reduce the severity ofS. hermonthica attack by direct suppression ofStriga growth and development at the post-germination stage and after shoots have been formed.     

盐基离子对土壤持水及收缩特性的影响

不同盐离子对土壤持水能力具有不同程度影响,且在土壤水分特征曲线测定过程中,土体随失水发生收缩和开裂。在已获取研究成果基础上进行扩展,进一步探索8种低浓度盐离子(K~+、Na~+、Ca~(2+)、Mg~(2+)、Cl~-、HCO_3~-、CO_3~(2-)、SO_4~(2-))对土壤持水能力和收缩特征的影响。选取陕西粉黏壤土并分别采用含有此8种离子的盐溶液(浓度均约为1 g·L~(-1))对土样进行饱和处理,以无盐离子处理作为对照(CK);采用离心机法获取土壤水分特征曲线,使用游标卡尺测定离心过程中的土体轴向沉降高度,编写MATLAB程序对裂缝图像提取裂隙度量指标,据此对各处理土壤持水能力和收缩特征进行对比分析及评价。结果发现,在此浓度条件下:(1)K~+、Na~+及4种阴性盐离子在一定程度上均可提高土壤持水能力,且阴阳盐离子中CO_3~(2-)和K~+效果最显著,分别较CK提高35.81%和3.68%;(2)Mg~(2+)、SO_4~(2-)和CO_3~(2-)有利于减小土体轴向收缩度,且阴阳盐离子的作用效果分别表现为HCO_3~-Cl~-SO_4~(2-)CO_3~(2-)和Na~+K~+Ca~(2+)Mg~(2+);(3)Na~+、Mg~(2+)及4种阴性盐离子在一定程度上均有利于减轻土壤开裂程度,可同时减小土壤裂隙总长度、总面积以及长度密度和面积密度,且阴阳盐离子中CO_3~(2-)和Na~+效果最显著。研究可为不同类型盐碱土壤持水能力评价及其干缩开裂机理认知提供理论指导。     

Sclerotinia sclerotiorum catalase SCAT1 affects oxidative stress tolerance,regulates ergosterol levels and controls pathogenic development

Reactive oxygen species (ROS) are essential for pathogenic development of Sclerotinia sclerotiorum. A key question for S. sclerotiorum and many other pathogens concerns how fungi tolerate/dampen the oxidative environment during growth and pathogenesis. Regulatory components of oxidative stress include both enzymatic and non-enzymatic antioxidants. Catalases are a ubiquitous family of enzymes that play an important role in the enzymatic detoxification of ROS by converting hydrogen peroxide (H₂O₂) to water and molecular oxygen. The genome of the omnivorous pathogen S. sclerotiorum contains seven predicted catalase genes. In this study we evaluate and functionally characterize the type A catalase (Scat1) in S. sclerotiorum, whose expression is highly induced during host infection. Insertional inactivation of Scat1 (ΔScat1) resulted in hyperbranching of hyphae accompanied by slower growth and smaller sclerotia. ΔScat1 strains were attenuated in pathogenicity and rendered the fungus hypersensitive to Sodium dodecyl sulfate (SDS), as well as to osmotic and salt stresses. Unexpectedly, ΔScat1 exhibited increased tolerance to H₂O₂, suggesting that although a member of the catalase family, generally associated with amelioration of oxidative stress, Scat1 is probably not required for detoxification of this oxygen species and presumably has different function(s). ΔScat1 strains had a 2-fold decrease in ergosterol content, and overall lower sterol levels compared to the wild-type strain. These observations are consistent with increased resistance to the polyene drugs amphotericin-B and nystatin. Taken together, our results suggest Scat1 is involved in modulation of ROS in a manner that deviates from the detoxification of H₂O₂, alters membrane integrity and contributes to the pathogenic success of S. sclerotiorum.     

Methylparathion- and carbofuran-induced mitochondrial dysfunction and oxidative stress in Helicoverpa armigera (Noctuidae: Lepidoptera)

The cotton bollworm, Helicoverpa armigera is a polyphagous pest of several crops in Asia, Africa, and the Mediterranean Europe. Organophosphate and carbamate insecticides are used on a large-scale to control Helicoverpa. Therefore, we studied the effect of methylparathion and carbofuran, an organophosphate and carbamate insecticide, respectively, on oxidative phosphorylation and oxidative stress in H. armigera larvae to gain an understanding of the different target sites of these insecticides. It was observed that state III and state IV respiration, respiratory control index (RCI), and P/O ratios were inhibited in a dose-dependent manner by methylparathion and carbofuran under in vitro and in vivo conditions. Methylparathion and carbofuran inhibited complex II by ∼45% and 30%, respectively. Lipid peroxidation, H₂O₂ content, and lactate dehydrogenase (LDH) activity increased and glutathione reductase (GR) activity decreased in a time- and dose-dependent manner in insecticide-fed larvae. However, catalase activity was not affected in insecticide-fed larvae. Larval growth decreased by ∼64% and 67% in larvae fed on diets with 100 μM of methylparathion and carbofuran. The results suggested that both the insecticides impede the mitochondrial respiratory functions and induced lipid peroxidation, H₂O₂, and LDH leak, leading to oxidative stress in cells, which contribute to deleterious effects of these insecticides on the growth of H. armigera larvae, along with their neurotoxic effects.     

种植年限对新疆盐碱土苹果园土壤质量及果实品质的影响

通过对不同种植年限盐碱地苹果园土壤理化指标及果实品质的测定,研究苹果种植年限和土壤理化性质特征间的关系及苹果品质的变化趋势。结果表明,研究区盐离子类型及含量组成是HCO_3~-SO_4~(2-)Cl~-Ca~(2+)Na~+Mg~(2+)K~+,土壤为高盐高碱类型。随着苹果种植年限的增加,土壤有机质、全氮、碱解氮含量显著升高,有效钾和有效磷含量在连续种植9 a后,相对于第1 a种植,含量分别增加了2.9和2.3倍。土壤中Ca、Fe含量总体呈降低趋势,种植1 a条件下土壤Ca、Fe含量较种植9 a条件下分别降低了8%和45.6%。土壤中SO_4~(2-)和Cl~-含量逐渐减小,其中SO_4~(2-)在种植1 a时含量最高,值为515.5 mg·kg~(-1),Ca~(2+)、Na~+、Mg~(2+)含量分别下降了62%、78%、79%。种植12 a的苹果可溶性固形物和单果重较种植4 a苹果分别增加了10.0%和28.8%。因此,苹果种植有利于降低新疆盐碱土的盐离子含量,提高其有机质、全氮、碱解氮含量,果实品质随种植年限延长进一步改善。     

羊草和脱硫石膏对内蒙古河套地区盐渍化土壤的改良效果

为了解脱硫石膏和耐盐植物改良与培肥盐渍化土壤的作用与效果,在内蒙古河套地区硫酸盐盐渍化土壤上设置田间试验,测定施用脱硫石膏(30 t·hm-2)与不施用脱硫石膏并种植羊草后土壤盐分及基础理化性质的变化。结果表明:春季灌溉可大幅度降低土体p H值、电导率(EC)和盐分离子浓度,施用脱硫石膏可加快降低土壤碱度,主要盐分离子Na+和SO42-分别降低了80%和39%以上,但EC略有提高,导致养分淋失;羊草对脱硫石膏有良好的反应,生物量提高了30%,但全磷含量降低了22%,全氮、全钾含量没有显著变化;种植羊草降低Na+和SO42-含量至3.38 mg·kg-1和132.27 mg·kg-1,且土壤有机质和碱解氮含量分别提高了12%和37%,同时施用脱硫石膏效果更好一些。说明脱硫石膏与羊草之间具有一定的相互作用,可加速盐渍化土壤改良的进程,但需要注意的是应适当增加施用P、K肥料,以补充养分不足。     

Comparative antifungal activities and biochemical effects of monoterpenes on plant pathogenic fungi

The antifungal activity of twelve monoterpenes, camphene, (R)-camphor, (R)-carvone, 1,8-cineole, cuminaldehyde, (S)-fenchone, geraniol, (S)-limonene, (R)-linalool, (1R,2S,5R)-menthol, myrcene and thymol was evaluated against four plant pathogenic fungi Rhizoctonia solani, Fusarium oxysporum, Penecillium digitatum and Asperigallus niger by using mycelial growth inhibitory technique. (S)-limonene and thymol were examined for their inhibitory effects on pectin methyl esterase (PME), cellulase and polyphenol oxidase (PPO) of tested fungi. Thymol was the most potent antifungal compound against the four test fungi with EC₅₀ values of 33.50, 50.35, 20.14 and 23.80 mg/L on R. solani, F. oxysporum, P. digitatum and A. niger, respectively. The antifungal activity of thymol was comparable to a reference fungicide, carbendazim. (S)-limonene and 1,8-cineole exhibited pronounced antifungal activity against the four tested fungi. The most effective antifungal compounds thymol and (S)-limonene showed strong inhibitory effect on the activity of PME and cellulase but revealed no inhibitory effect on PPO. The results showed that PME was more sensitive than cellulase to thymol and (S)-limonene. This is the first report on the inhibitory effects of monoterpenes thymol and (S)-limonene on PME, cellulase and PPO. The results indicated that monoterpenes may cause their antifungal activity by inhibiting PME and cellulase. The strong antifungal activity of thymol, (S)-limonene and 1,8-cineole reported in this study indicated that these compounds have a potential to be used as fungicides.     

The effect of hydrogen peroxide on the viability of tomato cells and of the fungal pathogen Cladosporium fulvum

An oxidative burst was previously demonstrated to be induced in tomato plants by race specific elicitors of the fungal pathogen Cladosporium fulvum . The in planta levels of H₂O₂estimated to occur during elicitor treatment, were compared with the levels required to show toxicity to host cells and to the fungal pathogen. Injection of Cf-9 tomato leaves with 100 m m H₂O₂caused an insignificant degree of necrosis and 1m H₂O₂was required to cause complete leaf necrosis comparable to that induced by the AVR9 elicitor. Assays with Cf-5 tomato cell suspensions confirmed the low toxicity of H₂O₂to tomato cells but, as expected, the addition of Fe²⁺with H₂O₂(or with intercellular fluids containing AVR5 elicitor) enhanced cell death as determined by the Evans Blue assay. Germination and germ tube growth of conidia of C. fulvum were significantly retarded by 4–5 m m H₂O₂, and at higher concentrations, death of germ tubes was observed (ED₅₀=22 m m), as determined by the fluorescein diacetate assay. The addition of Fe²⁺with H₂O₂had little effect on fungal growth or viability in vitro . These results suggest that the amount of H₂O₂accumulating during an elicitor-induced response in leaves may be sufficient to affect fungal colonization but not to affect viability of host cells unless the Fe²⁺status in the apoplast is in some way altered by the elicitor to facilitate OH^.production via the Fenton reaction.     

Synthesis and fungitoxic activity of 5‐aryl‐1‐formyl‐4,5‐dihydro‐3‐(2‐hydroxyphenyl)‐1H‐pyrazoles and their complexes

Cyclization of 3‐aryl‐1‐(2‐hydroxyphenyl)prop‐2‐en‐1‐ones with hydrazine hydrate in refluxing formic acid afforded the title ligands, 5‐aryl‐1‐formyl‐4,5‐dihydro‐3‐(2‐hydroxyphenyl)‐1H‐pyrazoles (HL¹–HL⁴, Ar = Ph, 4‐CH₃O‐C₆H₄‐, 2‐furyl, 2‐thienyl). Reaction of HL¹–HL⁴ with the divalent metal ions, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺, afforded novel complexes of the type [ML₂] (M = metal ion; L = deprotonated ligand) which were characterized by elemental analyses, molecular weight determinations, molar conductances, magnetic moments and electronic and infrared spectral data. The ligands behaved as tridentate, coordinating through the phenolic oxygen after deprotonation, N‐2 of the pyrazole ring and oxygen of the 1‐formyl group. The ligands and their complexes were evaluated for growth‐inhibiting activity against four phytopathogenic fungi. Macrophomina phaseoli was generally most sensitive followed by Alternaria alternata and Colletotrichum falcatum while Fusarium oxysporum was least sensitive to the tested compounds. The ligand HL¹ and its complexes showed the best activity against the fungi tested. © 2000 Society of Chemical Industry     

Studies on pesticides based on coumarin. II. Synthesis and antifungal activity of ten 2-alkyl-7, 8-dihydro-3-hydroxynaphtho[1,2-c]chromen-6-ones

A series of 2-alkyl-7, 8-dihydro-3-hydroxynaphtho[1,2-c]chromen-6-ones was synthesised by the condensation of ethyl 3, 4-dihydro-1-oxonaphthalene-2-carboxylate with substituted phenols in the presence of POCl₃. The compounds were characterised and tested for their toxicity towards the mycelial growth of seven phytopathogenic fungi in culture. Drechslera oryzae, Rhizoctonia solani and Colletotrichum falcatum exhibited maximum sensitivity to these compounds whereas Macro-phomina phaseolina, Fusarium solani, Alternaria alternata and Pythium aphanidermatum were less sensitive. 2-Ethyl-7, 8-dihydro-3-hydroxy-naphtho[1,2-c]chromen-6-ones possessed greatest toxicity with EC₅₀ values ranging from 0.2 to 2.5 μg ml^?1 against all fungi except A. alternata and P. aphanidermatum.     

盐碱胁迫对盐生植物种子萌发的影响

采用不同浓度的NaCl(中性盐)和Na2CO3(碱性盐)胁迫三种盐生植物盐地碱蓬、碱蓬和盐爪爪正在萌发的种子,以研究不同类型盐对种子萌发特性的影响.结果表明,随着两种盐浓度的升高,种子萌发率下降,萌发率与盐浓度间呈现显著的负相关关系;盐地碱蓬、碱蓬和盐爪爪种子萌发率与NaCl胁迫相关系数分别为0.9206、0.8989和0.8956,与Na2CO3胁迫相关系数分别为0.9148、0.7193和0.6327;蒸馏水中三种盐生植物种子萌发率最高,Na2CO3对种子萌发的抑制作用强于NaCl.     

Inhibition by aluminum of mycelial growth and of sporangial production and germination inPhytophthora infestans

Mycelial growth on clarified V8 agar of the potato late blight pathogenPhytophthora infestans was inhibited when either aluminum chloride (AlCl₃, 6 H₂O) or aluminum sulfate (Al₂(SO₄)₃, 18 H₂O) was added to the culture medium at concentrations of 2.5–100 mg.l^–1 Al³⁺. Toxicity of Al³⁺ varied among the fiveP. infestans isolates tested, but toxicity of sulfate and chloride salts was similar for a given isolate. Overall sporangial production was affected in all five isolates by both Al³⁺ forms. Al³⁺ also decreased sporangial germination at concentrations equal to or greater than 10 mg.l^–1 in two isolates. These data support the hypothesis of aluminum toxicity as a major factor in soil suppressiveness toP. infestans.     

Studies on pesticides based on coumarin. III. Synthesis and antifungal activity of substituted 4-methyl-coumarins and related compounds

A series of substituted 4-methylcoumarins was synthesised and the members tested for their toxicity towards mycelial growth of seven phytopathogenic fungi in culture. Rhizoctonia solani, Alternaria alternata and Fusarium solani exhibited maximum sensitivity to these compounds whereas Pythium aphanidermatum, Colletotrichum falcatum, Drechslera oryzae and Macrophomina phaseolina were relatively less sensitive. 6-Ethyl-3-n- propyl-7-hydroxy4-methylcoumarin ( I ) was relatively toxic towards all fungi except C. falcatum, P. aphanidermatum and M. phaseolina. The 6-n-butyl ( III ) and 6-(1, 1, 3, 3-tetramethylbutyl) ( VI ) derivatives were highly toxic to R. solani with EC₅₀, values of lμg ml^?1.