玉米象(Sitophilus zeamais Motschulsky)是世界性的储粮害虫,每年都造成严重的粮食损失.磷化氢是防治储粮害虫的主要熏蒸剂之一,由于长期使用,害虫对其已经产生了严重的抗药性.因此,急需寻求新的储粮害虫防治策略,一些挥发性小分子酯类化合物具有作为熏蒸剂的潜能.因此,本研究系统的评价30种酯类化合物对玉米象的熏杀活性.结果表明乙酸肉桂酯、甲酸香叶酯和乙酸烯炳酯对玉米象的熏杀活性最高,其LC50分别为0.32、1.82、1.92 μl/L.因此,乙酸肉桂酯、甲酸香叶酯和乙酸烯丙酯可以作为防治玉米象的潜在药剂.

采用水蒸气蒸馏法从龙脑樟的叶和茎中提取挥发油,通过气相色谱-氢火焰离子化法(GC-FID)和气相色谱-质谱联用(GC-MS)技术对其化学成分进行鉴定,用归一化法测定挥发油中各组分的相对百分含量,并评价其抗烟草花叶病毒(TMV)和抗菌活性.从龙脑樟叶的挥发油中共分离鉴定了28种挥发性化合物,其中d-冰片含量最高,达到68.45％,其他主要成分为樟脑(14.22％)、异丁香烯(4.65％)和(E)-β-石竹烯(2.00％)等;茎挥发油分离鉴定了17种成分,主要成分是d-冰片(64.02％)、樟脑(17.60％)和异丁香烯(5.39％)等.龙脑樟挥发油对TMV有抑制作用,在100μg/mL时抑制率达56.9％;对金黄色葡萄球菌、蜡状芽孢杆菌、大肠杆菌、烟曲霉和白色念珠菌均有较强的抑制作用,对烟曲霉的抑制能力最强,MIC值为31.3μg/mL.

Detailed chemical constituents of essential oil from the Pterocephalus hookeri leaves and its antimicrobial activities were investigated in this study. The essential oil, obtained by hydrodistillation, was characterized by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry analyses. Among the 90 identified compounds, hexadecanoic acid (21.27%), phytol (8.03%), furfural (7.08%), oleic acid (5.25%), and phytone (4.56%) were the major components. In the antimicrobial assay, the essential oil showed strong inhibitory activities against Escherichia coli, Candida albicans, and Staphylococcus aureus with minimum inhibitory concentration values of 31.3, 62.5, and 125 µg/mL, respectively. To our knowledge, this is the first report concerning chemical composition and antimicrobial activities of the essential oil from Pterocephalus hookeri.

为了评价不同春玉米品种的耐密性,以20个玉米品种为材料,设置5.25万株/hm2、6.75万株/hm2 2个密度处理,对不同玉米品种耐密性进行分析.主成分分析结果表明,将10个农艺性状转化为3个主成分因子,可代表原始数据信息量的86.77％,筛选出3个耐密性评价指标,即茎秆压折强度、穗位高系数和倒伏率;金玉306、金玉838、仲玉3号、黔单16号、正红6号和先玉1171这6个品种耐密性较好,适合在西南地区推广种植.聚类分析结果表明,20个玉米品种可划分成3类,结果与主成分分析得出的结论基本一致.本研究为西南地区选择耐密抗倒伏玉米品种提供参考依据.

To explore the mechanism of defense and resistive ability of a new polyene macrilide antibioticsagricultural antibiotic 702 on rice pathogenic fungi.We spray five different concentrations of agricultural antibiotic 702 on the booting rice with four or five leaves,at the same time,we used the concentration of jinggangmycin is 125 μg/mL as positive comparison and water as negative comparison.After 0,1,3,5,7,9 days,we picked the rice leaves and extracted its five defense enzymes and determined their activities.The activities of SOD,POD,PPO,CAT,PAL in rice leaves after we spray a series of concentrations(75,100,125,150 and 175 μg/mL) of agricultural antibiotic 702 and the 125 μg/mL jingangmycin were significantly higher than blank control.The five defense enzymes of rice deal with the agricultural antibiotic 702(125 μg/mL) reached and exceed the treatment with 125 μg/mL jingangmycin.Agricultural antibiotic 702 can induce the rice get the systemic acquired sistanee.The result of this experiment was useful for the further research of disease prevent mechanism of agricultural antibiotic 702.