Inhibition of ammonia-oxidizing bacteria promotes the growth of ammonia-oxidizing archaea in ammonium-rich alkaline soils

Disparities in the substrate affinity and tolerance threshold for ammonia have been believed to play a key role in driving niche differentiation between ammonia-oxidizing archaea (AOA) and bacteria (AOB); however, recent surveys argue that direct competition between AOA and AOB is also important in this phenomenon. Accordingly, it is reasonable to predict that diverse AOA lineages would grow in ammonium (NH₄⁺)-rich alkaline arable soils if AOB growth is suppressed. To test this hypothesis, a microcosm study was established using three different types of alkaline arable soils, in which a high NH₄⁺ concentration (200 μg N g^-1 dry soil) was maintained by routinely replenishing urea and the activities of AOB were selectively inhibited by 1-octyne or 3,4-dimethylpyrazole phosphate (DMPP). Compared with amendment with urea alone, 1-octyne partially retarded AOB growth, while DMPP completely inhibited AOB. Both inhibitors accelerated the growth of AOA, with significantly higher ratios of abundance of AOA to AOB observed with DMPP amendment across soils. Nonmetric multidimensional scaling analysis (NMDS) indicated that different treatments significantly altered the community structures of both AOA and AOB and AOA OTUs enriched by high-NH₄⁺ amendment were taxonomically constrained across the soils tested and closely related to Nitrososphaera viennensis EN76 and N. garnensis. Given that these representative strains have been demonstrated to be sensitive to high ammonia concentrations, our results suggest that it is the competitiveness for ammonia, rather than disparities in substrate affinity and tolerance threshold for ammonia, that drives niche differentiation between these phylotypes and AOB in NH₄⁺-rich alkaline soils.     

无人机飞行高度对植被覆盖度和植被指数估算结果的影响

将无人机与多种成像传感设备相结合可实现田间作物表型信息的全面获取。针对田间复杂环境下无人机搭载多种成像传感设备在不同飞行高度处提取的作物信息具有差异性的问题,本研究着重探究了无人机搭载两种成像传感设备获取图像时,不同飞行高度对估算植被覆盖度以及植被指数结果的影响。首先为防止外界环境变化对获取图像质量造成干扰,通过最近邻插值算法将无人机飞行高度为25 m处获取的两个多光谱和可见光图像数据集分别退化为十个不同地面分辨率的模糊图像数据集,以模拟无人机在不同飞行高度中获取的作物图像。然后获取50m高度处的无人机图像数据集通过皮尔逊相关性分析验证模拟数据集的有效性。最后采用随机森林模型估算不同数据集中的植被覆盖度,分类精度大于91%。结果发现,当植被覆盖度小于二分之一时,随着地面分辨率的降低该指标不断被低估,反之则被高估。飞行高度50 m的真实图像与模拟图像估算植被覆盖度结果的相关系数r为0.992 8,两者具有强相关性,模拟图像估算得到的植被覆盖度变化具备参考意义。植被指数估算结果中,首先对无人机图像数据集进行辐射校正、阈值分割等图像预处理,然后根据公式计算得到植被指数,最后通过假设性检验对十个图像数据集计算得出的植被指数进行分析。结果发现,可见光植被指数在飞行高度61 m时具备显著性差异,多光谱植被指数在十个高度下均没有显著性差异,因此为保证无人机获取数据的准确性与完整性,建议当无人机搭载本文的两种相机获取作物信息时建议飞行高度不高于61 m。本研究为研究者利用无人机搭载多传感设备获取作物信息设定合适的飞行高度、减小作业成本提供参考。     

柑橘黑点病菌种群对嘧菌酯敏感性基线的建立

为明确柑橘黑点病菌Diaporthe citri对嘧菌酯的敏感性以及嘧菌酯在我国柑橘黑点病防治中的应用潜力,分别采用菌丝生长抑制法和孢子萌发抑制法测定了来自浙江、湖南、江西、贵州4个主要柑橘产区的66个柑橘黑点病菌菌株对嘧菌酯的敏感性,并建立了其种群对嘧菌酯的敏感性基线。结果显示：嘧菌酯对柑橘黑点病菌菌丝生长和孢子萌发的EC₅₀平均值分别为(0.228 5±0.113 8)μg/mL和(0.025 6±0.006 9)μg/mL,种群对嘧菌酯的敏感性频次分布曲线为连续的单峰型,符合正态分布。因此可将嘧菌酯对这66个菌株的菌丝生长和孢子萌发的平均EC₅₀作为柑橘黑点病菌对嘧菌酯的敏感性基线,该敏感性基线可作为监测田间柑橘黑点病菌对嘧菌酯敏感性变化的参考,对指导今后科学用药具有现实意义。同时,本研究所使用的66个菌株对嘧菌酯敏感性均较高,没有抗性菌株出现,表明未来可以将嘧菌酯用于柑橘黑点病的防治,作为黑点病防治主打药剂代森锰锌的一种补充。     

国外引进盆栽芍药品种在杭州的生长观测及筛选

以从荷兰引进的8个盆栽芍药品种为试验材料,中国传统盆栽品种‘大富贵’为参照材料,对9个芍药品种在杭州盆栽2年的株高、分株数、开花数、成活率等数量指标运用隶属函数法进行分析,结合绿叶期、茎秆直立性和花型等性状指标进行综合评价。结果表明:9个芍药品种连续2年多在杭州夏季高温高湿气候条件下盆栽的成活率为100%;‘Kiev’、‘Dublin’、‘Oslo’和‘Athens’的株型紧凑、茎秆粗壮、成花率高、绿叶期长、生长健壮,可作为江南地区盆栽芍药的优良品种进行推广。     

γ-氨基丁酸茶的研究进展

茶的保健功能已被广泛认可,茶叶新产品的开发也日益受到重视.GABA因其具有降血压、抗焦虑、降低胆固醇、增强记忆力和促进血液中乙醇分解等多种功效已引起各界关注.二十多年来,经动物实验和临床实验证实,γ-氨基丁酸茶具有显著的降血压功能,日渐得到了市场的欢迎.本文综述了茶树中GABA的代谢途径、鲜叶中GABA的富集技术以及富集机理,并在此基础上指出γ-氨基丁酸茶开发中仍存在的问题,并对其前景进行了展望.     

不同地区红茶特异性香气成分比较研究

采用固相微萃取（HS-SPME）结合气质联用（GC-MS）技术,对比分析了中国及印度、斯里兰卡等不同地区7类红茶的香气组成及特异性香气成分.检测出149种挥发性香气物质,分析表明中国红茶香气化合物以醇类、醛类为主导,印度及斯里兰卡红茶中酯类、烯烃类相对含量明显较高.主成分分析能将不同地区红茶明显分为三类：1.安徽祁红、福建金骏眉表现出以香叶醇为主体的玫瑰花香;2.云南滇红、广东英德红表现出以芳樟醇为主的花果香、甜香;3.印度、斯里兰卡红茶体现以水杨酸甲酯为主的似薄荷冬青香气.品种特性、环境气候及加工工艺对香气特征有影响,不同地区红茶香气特异性风格明显.     

机采与手采鲜叶加工平水日铸茶工艺、品质及成本比较研究

在相同生产时间,对机采与手采鲜叶按连续化颗粒型加工工艺技术生产平水日铸茶,对生产的茶叶品质进行感官审评、成本进行比较分析,比较两种采摘模式下的加工方法、茶叶品质和经济效益。结果表明,机采鲜叶在嫩度与匀整度上明显低于手采鲜叶;可采用相同的初加工工艺与技术参数进行加工;机采毛茶品质由于含梗量与嫩度的原因在外形与叶底上感官审评得分略低于手采毛茶,但在香气与滋味上接近、有的甚至还稍优于手采毛茶,综合品质两者接近;精加工后两者品质更趋一致。在生产成本与得率上,每公斤机采茶的成本比手采茶低36.22%,得率低25.48%,经济效益高约21.30%。     

茶树遗传育种研究新进展（2013）

本文从茶树遗传资源研究、茶树品种选育研究、育种鉴定和诱变技术研究、分子生物学技术应用研究以及良种良法技术研究等方面综述了2013年中国茶树遗传育种研究的进展;从茶树再生系统构建、茶树育种鉴定技术研究和分子生物学技术应用等方面综述了国外茶树育种研究进展.     

Methylthio-Aspochalasins from a Marine-Derived Fungus Aspergillus sp.

Two novel aspochalasins, 20-β-methylthio-aspochalsin Q (named as aspochalasin V), (1) and aspochalasin W (2), were isolated from culture broth of Aspergillus sp., which was found in the gut of a marine isopod Ligia oceanica. The structures were determined on the basis of NMR and mass spectral data analysis. This is the first report about methylthio-substituted aspochalasin derivatives. Cytotoxicity against the prostate cancer PC3 cell line and HCT116 cell line was assayed using the MTT method. Apochalasin V showed moderate activity at IC₅₀ values of 30.4 and 39.2 μM, respectively.     

First results on migrating shad (Alosa fallax) and mullet (Mugil cephalus) echocounting in a lock on the Rhône River (France) using a split-beam sounder,and relationships with environmental data and fish caught

The application of fisheries acoustics in shallow waters opens new fields of observation and allows new methods for abundance estimates. In this paper we deal with echocounting of migrating fish crossing the Beaucaire-Vallabrègues lock, the first obstacle encountered on the Rhône, using a SIMRAD EY500 split-beam sounder, 70 kHz frequency. Two transducers sampled a section of water and evaluated approximately 35% of the lock section, based on a calibration sphere. The number of fish crossing the lock was calculated for each fish lock. Crossing data for the fish were recorded (dates, position, exit time). The present analysis did not allow the identification of the two major species that cross the dam: shad (Alosa fallax) and mullet (Mugil cephalus). The number of fish counted was positively correlated with the catches per unit effort (CPUE) by recreating fishermen below the dam and with increasing water temperature.