假蒟提取物杀虫活性成分稳定性研究

采用常规浸提法对假蒟植株根茎部分进行提取,以提取物中杀虫成分对斜纹夜蛾3龄幼虫的活性作为评价指标,综合评价了不同pH、不同温度和光照环境对假蒟提取物杀虫活性成分稳定性的影响。结果表明,不同pH环境对假蒟提取物杀虫活性成分影响不大;在高温环境中,其活性有所下降;在不同光源处理中,影响较为严重的是太阳光,经照射处理72h后,杀虫活性效果由93.33%变为27.78%。在此基础上,评价了11种常用光稳定剂的光分解抑制效果,结果发现,所评价的光稳定剂均具有一定抑制效果,其中以光稳定剂622和抗氧化剂TBHQ抑制效果较为明显。在此基础上,进一步评价了不同浓度622和TBHQ抑制效应差异,结果显示抑制效果与浓度相关,浓度越高,抑制效果越明显。     

玫瑰黄链霉菌Men-myco-93-63活性代谢产物roflamycoin的光稳定性分析

为研究影响玫瑰黄链霉菌Streptomyces roseoflavus Men-myco-93-63活性代谢产物roflamycoin光不稳定的因素,采用高效液相色谱仪测定了不同光照环境、光照强度、光照时间、溶剂、质量浓度等因素下roflamycoin的光分解率;检测8种光稳定剂对roflamycoin光分解的抑制作用;并通过抑菌圈法测定了光分解前后物质抑菌效果的变化。结果显示,在roflamycoin的光分解过程中,太阳光和日光灯是其敏感光源,而紫外光并不能引起光分解;光照强度越大、光照时间越长、质量浓度越低,其光分解速率越快;在甲醇、丙酮、N,N-二甲基甲酰胺、二甲基亚砜、四氢呋喃5种溶剂中的光分解速率无显著差异;roflamycoin光分解过程最终可以达到一个稳定状态,主要分解为3种物质,并与roflamycoin具有相同的五烯大环内酯骨架;8种光稳定剂均未表现出抑制光分解的作用。roflamycoin光照分解后对12种病原菌仍有抑制作用,其中对番茄灰霉病菌、玉米穗腐病菌等6种病原菌的抑制活性显著增强,抑菌圈直径增大7.64%～21.91%,对棉花黄萎病菌、苹果斑点落叶病菌等4种病原菌的抑制活性显著降低,抑菌圈直径减小10.03%～91.46%。推测roflamycoin的光分解产物仍具有抑菌活性。     

不同光波长对水中乙草胺光分解的影响

以高压汞灯和太阳光为光源,以不同波长滤光片处理得相应波长区域,研究了乙草胺在水中的光解动态。结果表明:在胡敏酸存在下,乙草胺的光解动态符合一级动力学规律,其光解速度随着照射光波长的延长而减慢,光解半衰期延长,与未用滤光片处理的对照相比,差异极显著,表明乙草胺在水中的光解速度与照射光波长关系极大。     

苦豆子内生真菌对宿主培养物生长及喹诺里西啶类生物碱合成的影响

利用苦豆子健康植株中分离鉴定的8株内生真菌菌株为真菌诱导子,分别制备灭活菌丝和菌液浓缩物,研究内生真菌诱导子不同种类、浓度和诱导时间对苦豆子无菌苗和愈伤组织的生长以及喹诺里西啶生物碱含量的影响。结果表明:8株苦豆子内生真菌诱导子中,菌液浓缩物的诱导效果要强于灭活菌丝。菌株HMGKDF1菌液浓缩物和灭活菌丝都能明显促进愈伤组织的生长,净生长率是对照的1.82和1.42倍;菌株NDZKDF13菌液浓缩物对愈伤组织生物碱的合成效果明显,生物碱含量为0.5483 mg·g-1,是对照的23.8倍;在一定浓度范围内(0.01~1.0 mg·L-1),苦豆子内生真菌诱导子能够促进宿主植物喹诺里西啶生物碱的合成。内生真菌诱导子处理苦豆子无菌苗12 d时,喹诺里西啶生物碱含量最高,是对照的2.65倍。在苦豆子无菌苗或愈伤组织中添加一定量的苦豆子内生真菌诱导子,对宿主的生长以及提高喹诺里西啶生物碱含量是一种有效的方法。     

不同盐分梯度下胡杨幼苗的光合-光响应特征

通过分析不同盐分处理60 d胡杨幼苗的光响应特征。结果表明：① 在0~3 500 μmol•m^-2•s^-1光强范围,各处理幼苗的净光合速率(P _n)、气孔导度(G_s)、蒸腾速率(T_r)和水分利用效率(WUE)[WTBZ]均随光强增加逐渐增大,而胞间CO₂浓度(C_i)呈相反趋势;不同光强下幼苗的P _n、G_s、T_r、C_i 和WUE均[值均随盐浓度增大而减小;低盐浓度处理(0.5 mol•L^-1)条件下,幼苗通过气孔调节提高WUE,降低盐分对幼苗的损伤;高盐处理(2 mol•L^-1),气孔基本失去调节能力,出现了Tr相对较低、WUE相对较高的现象,而幼苗的Pn[WTBZ]均值降低了约75%,幼苗的光合代谢受到严重抑制。② 随盐浓度增大,胡杨幼苗的最大净光合速率(Pnmax)、表观量子效率(α)、暗呼吸速率(Rd)和光饱和点(LSP)逐渐降低,光补偿点(LCP)逐渐增加,盐分抑制了幼苗对光的吸收、利用和转换能力。     

NaCl胁迫对蓖麻功能叶光系统Ⅱ荧光特性的影响

以中科院自育蓖麻品种KB-7号为试验材料采用室外盆栽法,研究了不同浓度Na Cl盐胁迫对其功能叶片叶绿素荧光参数的影响及其光响应曲线。结果发现:在高浓度Na Cl(9g·kg-1)胁迫时,蓖麻幼苗叶片光系统II(PSII)最大光化学量子效率(Fv/Fm)显著下降;随着光强的增加,Y(NPQ)、ETR、NPQ上升,Y(II)、qp等荧光参数显著下降,Y(NO)保持稳定。以上结果表明,蓖麻在低浓度Na Cl(0-6g·kg-1)处理下通过自身的调节机制避免盐离子对PSII反应中心造成伤害,高浓度Na Cl(9g·kg-1)盐胁迫处理引发光合电子传递受阻,导致PSII反应中心关闭或不可逆失活,表现出光抑制现象。     

蓖麻提取液对甜菜夜蛾幼虫解毒酶活性的影响

为探讨植物提取液对甜菜夜蛾解毒酶系活性的影响效应,采用浸渍法测定了不同浓度蓖麻碱(3.80、1.90、0.95、0.48和0.24g/L)对甜菜夜蛾幼虫碱性磷酸酯酶(AKP)、酸性磷酸酯酶(ACP)和谷胱甘肽S-转移酶(GSTs)活性的影响。结果表明:与清水对照组相比,不同浓度处理48h和72h对AKP的抑制作用均达到显著水平,而3.80g/L处理24h即可显著抑制AKP活性;与对照组相比,不同浓度蓖麻碱处理72h均会显著降低其ACP活性,而浓度大于0.24g/L时处理24h和48h即可显著降低ACP活性;蓖麻碱处理组GSTs活性在处理后24、48和72h都显著低于对照组,但不同浓度间无显著差异;本研究揭示了蓖麻碱对这3种解毒酶均有较强的抑制作用,且抑制作用随蓖麻碱浓度升高和作用时间延长而增强。     

PEG胁迫对萌动苦豆子子叶抗旱生理及氧化苦参碱含量的影响

以PEG-6000模拟干旱条件,测定苦豆子种子萌发、萌动种子子叶中质膜相对透性(PMP)、丙二醛(MDA)和脯氨酸(Pro)含量以及抗氧化物酶POD、CAT、SOD酶活性以及氧化苦参碱含量,探讨苦豆子种子的抗旱适应性。结果表明:10%PEG胁迫下,种子的发芽势、发芽率、发芽指数和活力指数均达到最高,依次为66.67%,78.67%,24.40和183.79,20%PEG胁迫种子仍有较高的发芽能力。随PEG胁迫程度加剧,萌动苦豆子种子子叶中质膜相对透性和Pro含量逐渐上升,MDA含量逐渐下降;POD、CAT和SOD 3种保护酶对干旱胁迫的保护作用不尽相同,中轻度胁迫(PEG≤20%)时POD酶起主要作用,重度胁迫(PEG20%)时CAT和SOD酶起主要作用。PEG胁迫使子叶中OMA含量下降,OMA含量与抗旱生理指标间均存在负相关。适度干旱有助于苦豆子种子萌发,萌动种子对干旱有强的防御机制。     

苦参生物碱对植物病原菌的离体抗菌活性研究

测定了苦参总碱(混和生物碱)及其单体苦参碱、氧化苦参碱、槐果碱、槐定碱、野靛碱等6个样品对11种植物病原真菌和3种细菌的离体抗菌活性。结果表明,在药剂浓度为500mg/L时,仅苦参总碱对黄瓜疫霉病和辣椒炭疽病菌、槐定碱对黄瓜疫霉病菌表现出较好的活性,菌丝生长抑制率分别为96.18%、54.90%、93.62%,苦参总碱和槐定碱对黄瓜疫霉病菌菌的EC50分别为178.21mg/L和162.13mg/L;6个样品对3种病原细菌的活性较低,在药剂浓度为100μg/mL时,生长抑制率均在20%以下。     

苦豆子7种生物碱对瓜类炭疽病菌的室内毒力测定

采用7种苦豆子生物碱单体对黄瓜炭疽病菌进行室内生物测定,筛选出对炭疽病菌有效的生物碱单体苦豆碱,与对该病菌高效的常规药剂多菌灵进行了比较,结果表明,苦豆碱对灰霉病菌的有效中浓度(EC50)为188.28mg/L,与多菌灵相当。     

Photolysis and hydrolysis of rimsulfuron

The degradation in the liquid phase of rimsulfuron and its commercial 250 g kg⁻¹ WG formulation (Titus®) was investigated. Photolysis reactions were carried out at 25 °C by a high-pressure mercury arc (Hg-UV) and a solar simulator (Suntest), while the hydrolysis rate was determined by keeping aqueous buffered samples in the dark. The effects of solvent and water pH on reaction kinetics were studied, and the results compared to literature data. Photoreactions of the commercial product in organic solvents were faster than pure rimsulfuron. Under simulated sunlight in water, the half-life for the photolysis reaction ranged from one to nine days at pH 5 and 9, respectively. The hydrolysis rate was as high as the photolysis rate, but decreased on increasing water pH. The main metabolite identified in neutral and alkaline conditions as well as in acetonitrile was N-[(3-ethylsulfonyl)-2-pyridinyl]-4,6-dimethoxy-2-pyridinamine, while N-(4,6-dimethoxy-2-pyrimidinyl)-N-[(3-(ethylsulfonyl)-2-pyridinyl)]urea and minor metabolites prevailed in acidic conditions. © 1999 Society of Chemical Industry     

Photolysis of chlorsulfuron and metsulfuron-methyl in methanol

Photolysis of chlorsulfuron and metsulfuron-methyl was studied in methanol under UV light. Their rates of primary photolysis followed first-order kinetics. The main photoproducts were identified as 2-methoxy-4-methyl-1,3,5-triazin-6-amine, 2-chloro-benzenesulfonamide and methyl 2-(aminosulfonyl)benzoate, which entailed the cleavage of the two N–C ureic bonds. Further photolysis of benzenesulfonamide derivatives involved oxidation of −NH₂, cyclisation with loss of CH₃OH, and scission of the C–S bond A trace of methyl o-mercaptobenzoate was also detected. The corresponding photolysis pathways of chlorsulfuron and metsulfuron-methyl were tentatively proposed. © 1999 Society of Chemical Industry     

乙草胺在水中的光化学降解动态研究

研究了乙草胺在100W中压石英汞灯的光照下的光解动态。结果表明，乙草胺在水溶液中的浓度越高，光解半衰期越长，溶液的pH越高，乙草胺越容易光解。溶液中的溶解氧对乙草胺的光解影响不大，乙草胺在空气饱和溶液中光解速度略快。在不同类型的水中，乙草胺的光解速率也不一样，乙草胺的浓度为20mg/L时，在去离子水，河水和稻田水中的光解半衰期分别为8．06，10．11，12．46min。乙草胺的主要光解产物是羟化乙胺，脱氯可能是乙草胺光解速率的决定步骤。     

Photolysis of Diuron

The major photoproducts observed in the photolysis of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] ( 2 ) in aqueous solution resulted from a heterolytic substitution of chlorine by OH (photohydrolysis). A wavelength effect was observed: at 254 nm the formation of 3-(4-chloro-3-hydroxyphenyl)-1,1-dimethylurea ( 3 ) accounted for more than 90% of the conversion, whereas when the solution was irradiated in ‘black light’ (85% of photons emitted at 365 nm, about 7% at 334 nm), the major photoproduct was 3-(3-chloro-4-hydroxyphenyl)-1,1-dimethylurea ( 4 ). The presence of methanol favoured the photoreduction into 3-(3-chlorophenyl)-1,1-dimethylurea ( 5 ). Completely different reactions were observed when 2 was irradiated in dry aerobic conditions on silica. They resulted from elimination or oxidation of methyl groups. The main photoproducts initially formed were 3-(3,4-dichlorophenyl)-1-methyl urea ( 6 ) and 3-(3,4-dichlorophenyl)-1-formyl-1-methylurea ( 7 ). In the second stage ( 6 ) was transformed into (3,4-dichlorophenyl)-urea ( 8 ) and 3-(3,4-dichlorophenyl)-1-formylurea ( 9 ); some other minor products such as monuron ( 1 ) were also identified. The formation rate of 6 and 7 was much slower on clay (montmorillonite or kaolin) than on silica. In contrast with products 6 and 8 , the formation of 7 and 9 needed the presence of oxygen: they did not appear when diuron was irradiated in deoxygenated C₂Cl₃F₃. It can be concluded that the photolysis of diuron is highly dependent on the conditions of irradiation. © 1997 SCI.     

大黄酚在水中的光解特性研究

实验室条件下,利用高效液相色谱研究了大黄酚在水中的光解特性。结果表明:大黄酚在水中光解符合一级动力学方程,25℃下,光照强度为4000 lx时,初始质量浓度为2.0、5.0、10.0mg/L大黄酚的半衰期分别为66、239、433h,即初始质量浓度越高,降解时间越长;5.0mg/L大黄酚在8000 lx光照强度下的半衰期为77h,说明光照强度越大,降解越快;在pH值为4、7、9的缓冲溶液中,5.0mg/L大黄酚的半衰期为107、71、3h,即偏酸条件对大黄酚的水中光解有一定的抑制作用,偏碱环境可显著促进大黄酚的水中光解。根据我国农药的光解特性等级划分标准,大黄酚在水中的光解性能为难光解。     

Photolysis of Diniconazole-M under Sunlight

The photodegradation of diniconazole-M [(E)-(R)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-pentene-3-ol] was studied as thin film on glass surface under sunlight. Photoproducts were separated and identified by NMR, IR, UV and mass spectroscopy. They were characterised as the (Z)-isomer of diniconazole-M, a cyclic alcohol and its corresponding ketone and an isoquinoline derivative. © 1997 SCI.