噁唑烷类安全剂的三维定量构效关系研究

针对25个噁唑烷类化合物,以玉米根部GST活性为衡量标准,运用三维定量构效关系中的比较分子力场分析(CoMFA)和比较分子相似性指数分析(CoMSIA)两种方法进行研究;应用20个化合物作为训练集,分别建立相应的模型,并对其进行结构和活性关系的分析。CoMFA模型的交叉验证系数q2为0.647,非交叉验证系数r2为0.999;CoMSIA模型交叉验证系数q2为0.527,非交叉验证系数r2为0.949。使用训练集以外的5个化合物进行了验证,两种模型预测值与实测值偏差较小,都显示出了较好的预测性和稳定性。研究结果可为设计新的噁唑烷类潜在的除草剂安全剂提供可靠信息。     

不同品种玉米对烟嘧磺隆的耐药性研究进展

烟嘧磺隆是广谱灭生性、内吸传导型除草剂,广泛应用于玉米苗期杂草的控制。由于不同品种玉米对烟嘧磺隆的耐药性不同,因此部分品种玉米因其发生严重药害的问题屡见报道。文章从烟嘧磺隆的作用机理、不同品种玉米对烟嘧磺隆的耐药性鉴定以及玉米抗烟嘧磺隆的遗传机制等方面进行了综述,阐述了目前对玉米抗烟嘧磺隆基因的定位尚不明确,烟嘧磺隆在玉米体内代谢机制的研究还比较困难等问题,认为未来可通过对玉米抗烟嘧磺隆内源基因的发掘以及实现基因的最终转化来提高不同品种玉米的耐药性。     

Mode of action of naphthalic anhydride as a safener for the herbicide AC 263222 in maize

In hydroponic experiments, seed-dressing with the herbicide safener 1,8-naphthalic anhydride (NA), significantly enhanced the tolerance of maize, (Zea mays L., cv. Monarque) to the imidazolinone herbicide, AC 263222, (2-[4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-5-methylnicotinic acid). Uptake, distribution and metabolism studies where [¹⁴C]AC 263222 was applied through the roots of hydroponically grown maize plants showed that NA treatment reduced the translocation of radiolabel from root to shoot tissue and accelerated the degradation of this herbicide to a hydroxylated metabolite. Reductions in the lipophilicity and, therefore, mobility of this compound following hydroxylation may account for NA-induced retention of radiolabel in the root system. Hydroxylation of AC 263222 suggested that NA may stimulate the activity of enzymes involved in oxidative herbicide metabolism, such as the cytochrome P₄₅₀ mono-oxygenases. In agreement with this theory, the cytochrome P₄₅₀ inhibitor, 1-aminobenzotriazole (ABT), synergized AC 263222 activity and inhibited its hyroxylation in vivo. NA seed-dressing enhanced the total cytochrome P₄₅₀ and b₅ content of microsomes prepared from etiolated maize shoots. Isolated microsomes catalyzed AC 263222 hydroxylation in vitro. This activity possessed the characteristics of a cytochrome P₄₅₀ mono-oxygenase, being NADPH-dependent and susceptible to inhibition by ABT. Activity was stimulated four-fold following NA seed treatment. Differential NA enhancement of AC 263222 hydroxylase and the cytochrome P₄₅₀-dependent cinnamic acid-4-hydroxylase (CA4H) activity, suggested that separate P₄₅₀ isozymes were responsible for each activity. These results indicate that the protective effects of NA result from enhancement of AC 263222 hydroxylation and concomitant reduction in herbicide translocation. This may be attributed to the stimulation of a microsomal cytochrome P₄₅₀ system. © 1998 SCI.     

玉米穗腐病防治药剂的室内毒力测定及田间防效

采用菌丝生长速率法进行7种杀菌剂对玉米穗腐病致病菌的毒力测定和田间病害防治试验,筛选对玉米穗腐病具有良好防控作用的药剂,为生产中病害治理提供依据。试验结果表明,禾谷镰孢Fusarium graminearum对戊唑醇最敏感,EC50为0.232 mg/L;拟轮枝镰孢F. verticillium对丙环唑最敏感,EC50为0.512 mg/L;青霉Penicillium sp.对吡唑醚菌酯表现敏感,EC50为1.522 mg/L;链格孢Alternaria alternata对戊唑醇表现敏感,EC50为0.354 mg/L。将丙环唑和吡唑醚菌酯按照1∶50的有效成分质量比进行混配,对抑制禾谷镰孢具有明显增效作用,共毒系数达到688.830;将丙环唑和吡唑醚菌酯按1∶20的有效成分质量比进行混配,对抑制拟轮枝镰孢具有明显增效作用,共毒系数达到500.220,并在室内盆栽试验中对玉米穗腐病的防治效果达到78.23%,田间试验中防治效果也达到74.27%。研究表明,在玉米灌浆期施用丙环唑和吡唑醚菌酯混剂,对于防治玉米穗腐病具有良好的效果。     

芽胞杆菌种衣剂对玉米茎基腐病的防治效果及对玉米的促生作用

为明确玉米内生细菌YY4和YG2菌株的生防应用潜力,采用滤纸片法测定两者对禾谷镰孢菌Fusarium graminearum和拟轮枝镰孢菌F. verticillioides的抑制作用,结合形态学特征、16S r DNA及gyrA基因序列分析对其进行鉴定,将菌株YY4与YG2的发酵液以体积比4∶1混合,再添加助剂制成生物种衣剂,设置3种药种质量比(1∶40、1∶50和1∶60)进行田间促生作用及防治效果的测定,并分析其对玉米产量的影响。结果表明,YY4菌株对禾谷镰孢菌和拟轮枝镰孢菌的抑制率分别为62.32%和59.83%,YG2菌株的抑制率则分别为63.40%和60.72%;YY4菌株被鉴定为贝莱斯芽胞杆菌Bacillus velezensis,YG2菌株被鉴定为耐盐芽胞杆菌B. halotolerans;这2株芽胞杆菌混合制成的生物种衣剂按药种质量比1∶50包衣处理后15 d,玉米的出苗率和株高分别为74.43%和5.16 cm,均显著高于空白对照和化学种衣剂50%克菌丹可湿性粉剂及15.5%福美双·克百威悬浮种衣剂包衣处理;且该处理对玉米茎基腐病的防治效果达68.89%,玉米产量分...     

不同杀菌剂对玉米白斑病的田间防治效果

玉米白斑病是我国西南玉米产区一种新发病害, 尚缺乏有效的防控措施。为筛选玉米白斑病的防控药剂, 本研究选用19种不同作用机制的杀菌剂, 于2022年－2023年在云南省普洱市开展田间试验, 分别于玉米10叶期和抽雄吐丝期采用叶面喷雾法施药1次, 评价各药剂的田间防效。结果显示, 9种防治真菌性病害的杀菌剂在最后1次施药后28 d对白斑病的防治效果超过50%, 包括250 g/L嘧菌酯悬浮剂、40%氟环唑悬浮剂、24%井冈霉素A水剂、40%咪鲜胺水乳剂和10%苯醚甲环唑微乳剂5种单剂, 以及325 g/L苯甲·嘧菌酯悬浮剂、40%丁香·戊唑醇悬浮剂、40%唑醚·戊唑醇悬浮剂和30%氟环·咪鲜胺微乳剂4种混剂。保护性杀菌剂代森锰锌和有机铜杀菌剂喹啉铜仅表现了23.26%和29.00%的微弱防效。卵菌病害特效药剂烯酰吗啉, 防治细菌性病害的杀菌剂春雷霉素、四霉素、中生菌素以及植物免疫诱抗剂6%寡糖·链蛋白可湿性粉剂的防效较差, 均低于20%。本研究发现部分甲氧基丙烯酸酯类和三唑类杀菌剂对玉米白斑病具有较好的田间防治效果, 建议现阶段在生产上采用二者的复配药剂如苯甲·嘧菌酯, 唑醚·戊唑醇等开展田间防控。     

玉米根系分泌物中关键抑菌物质对大豆疫霉的抑菌活性

间作是控制作物土传病害的有效手段,根系分泌物对病原菌生长的影响是间作具备控病效果的重要原因。本文研究了玉米根系对大豆疫霉游动孢子行为特征的影响,鉴定了玉米根组织中的关键抑菌活性物质,测定其对大豆疫霉菌丝生长和游动孢子行为的影响。结果表明,大豆与玉米间作能够显著降低大豆疫霉根腐病的发生,玉米根系和根系分泌物能够显著减弱根际大豆疫霉游动孢子的游动和根际大豆疫霉休止孢的萌发能力。通过HPLC对玉米根组织进行分析,发现玉米根组织中存在门布和苯并噻唑这两种抑菌物质,两者能显著抑制大豆疫霉游动孢子的游动和其休止孢的萌发能力;在浓度为500μg/mL时,其游动抑制率均达到100%;而萌发抑制率分别为100%和81%。同时,门布和苯并噻唑都能显著抑制大豆疫霉的菌丝生长。在浓度为500μg/mL时,其抑制率分别为100%和62.49%。综上所述,玉米根系组织中产生和分泌的门布和苯并噻唑对大豆疫霉具有抑菌活性,生产上可以利用玉米/大豆间作降低大豆疫病的危害。     

Protective role of propolis against reproductive toxicity of chlorpyrifos in male rats

Chlorpyrifos (CPF) is causing different toxicity and propolis has been reported to be an effective antioxidant. Therefore, the present study is aimed to elucidate the possible protective effects of propolis in alleviating the toxicity of chlorpyrifos on reproductive performance, testosterone levels, enzyme activities and lipids profile in serum of male rats. Animals were divided into four groups; one orally administered (o.d.) CPF at a dose of 9 mg/kg b.w. for consecutive 70-days, propolis group (50 mg/kg b.w.), propolis and chlorpyrifos group and a control group. Results showed that there was a correlation between CPF administration and the significant decrease of the sperm counts, spermatozoon survival and testosterone level as well as increase of sperm aberrations. CPF increased significantly the lipid profile and the levels of various serum liver marker enzymes. In contrast, co-administration of propolis to CPF-treated rats restored almost most of these biochemical parameters to normal levels. On the other hand, CPF resulted in histopathological alterations in testes of male rats. However, pre-administration of propolis to CPF-treated animals improved the testicular damage and alleviates the toxic effects of CPF on reproductive functions in male rats.     

异噁唑草酮对玉米根际土壤微生物量碳、氮和酶活性的影响

为明确异噁唑草酮对玉米根际土壤微生物碳、氮及酶活性的影响, 采用田间试验的方法, 以1倍、5倍和10倍田间推荐剂量为供试除草剂剂量, 测定了异噁唑草酮土壤封闭处理对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶、蔗糖酶、脱氢酶和中性磷酸酶活性的影响。结果表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量无显著影响, 5倍和10倍推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量具有抑制作用。推荐剂量的异噁唑草酮对玉米根际土壤脲酶、过氧化氢酶和蔗糖酶影响较小, 5倍和10倍推荐剂量的异噁唑草酮对其具有明显的抑制作用。异噁唑草酮对土壤脱氢酶活性具有抑制作用, 且施用剂量越高, 抑制作用越强。异噁唑草酮对土壤中性磷酸酶活性的影响表现为前期促进, 后期抑制, 且施用剂量越大, 促进或抑制作用越强。研究表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶和蔗糖酶活性的影响较小, 但对土壤脱氢酶、中性磷酸酶活性有影响。     

Effectiveness of cyfluthrin dust treatment for control and protection of shelled maize against infestation by the larger grain borer,Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in Tanzania

Abstract

Knockdown, mortality and residual activity of pyrethrins and cyfluthrin were studied on the larger grain borer (LGB), Prostephanus truncatus (Horn). Pyrethrum marc with 0.4% pyrethrins and cyfluthrin dust (0.1% a.i.) when applied on filter paper at 0.72 mg/cm² gave 98.6% and 100% knockdown (KD) respectively after 6 h. Cyfluthrin dust had a faster KD effect with 100% KD compared to 93.1% for pyrethrum marc, ½1/2>h after treatment. After 24 h there was no recovery from KD in both treatments. After 72 h, 23.2% of the LGB had recovered from KD while mortality was 76.8% in the pyrethrum marc treatment. After the same period, cyfluthrin resulted in 100% mortality. Mortality of P. truncatus exposed to different dosages of cyfluthrin dust in shelled maize was less than 100% at dosages lower than 1 part per million (ppm) but was 100% at 1 ppm and higher dosages 3 days after treatment. Progeny emergence was suppressed at all dosage levels above 0.25 ppm compared to a mean progeny of 68.8 in the check after 45 days. Cyfluthrin dust was more residually toxic at 0.5 ppm and higher dosages, with mortality of >90% at 5 months after treatment. This suggests that cyfluthrin dust at 0.1% a.i. mixed with shelled maize at 1 ppm will give protection and control of LGB infestation.     

细胞微丝骨架在玉米抗纹枯病菌Rhizoctonia solani 侵染中的作用

为探究细胞微丝骨架在玉米抗纹枯病侵染过程中的作用,采用微丝骨架解聚剂LatB预处理玉米离体叶片后接种立枯丝核菌Rhizoctonia solani AG1-IA,显微观察病原菌的侵染过程,并检测活性氧(ROS)、细胞坏死及抗病基因(PR1、ZmDREB2A)表达等抗病反应情况。结果显示,与未经LatB预处理相比,LatB预处理加快了R.solani侵染后玉米病斑的形成,并影响了侵染结构的发育;在侵染后期,LatB促进了R.solani诱导的玉米叶片中ROS积累、细胞坏死反应和PR1基因表达;溶剂DMSO预处理与未经LatB预处理的结果类似,表明DMSO对本试验的影响较小。研究表明,细胞微丝骨架不仅参与玉米抗R.solani的侵入,而且通过调控ROS、PR1基因表达,细胞死亡等抗病信号提高玉米抗病防御能力。本研究为进一步研究细胞微丝骨架在玉米对纹枯病的抗病机理中的作用提供了重要参考。     

基于Jensen模型的内蒙古河套灌区春玉米水分生产函数研究

为了系统分析玉米整个生育期不同时期水分亏缺对产量的影响,适时开展灌溉影响评估,基于Jensen模型和水量平衡方程,利用水分试验数据和历史观测资料研究了河套灌区玉米水分敏感指数、玉米需水量和最高产量,建立了需水量和水分敏感指数时间变化方程,包括三项式和Logisitic两种形式,在旬尺度上二者的模拟结果十分接近;通过回代和实例检验,估算产量与实测产量有较好的一致性,回代结果的相关系数在0.92以上,相对误差小于15%的样本占到80%;实例检验的相关系数在0.63~0.69之间,相对误差低于20%的样本占到80%~100%,模拟效果基本符合实际。