结实期相对高温对稻米淀粉粘滞性谱及镁、钾含量的影响

选用武育粳3号(粳稻)和扬稻6号(籼稻)两个水稻品种,利用人工气候室在水稻灌浆结实期进行控温试验,设置全结实期相对高温、结实前期相对高温、结实后期相对高温、全结实期适温(对照,日均温23 ℃)对照4个处理,探讨结实期不同时段相对高温(日均温度-30 ℃)对稻米淀粉粘滞性谱和Mg、K等元素含量的影响.结果表明：结实期相对高温使武育粳3号和扬稻6号淀粉粘滞性谱特征值发生改变,其中糊化开始温度、冷胶粘度、回复值和消减值升高,最高粘度、热浆粘度和崩解值下降;结实期相对高温促进了米粉中Mg、K、N含量的提高,特别是K含量的大幅提高,使稻米中Mg/K和Mg/(N·AC·K)明显降低;而2个水稻品种的直链淀粉含量（AC）对相对高温的反应截然相反,武育粳3号的AC降低、扬稻6号的AC升高.全结实期相对高温对稻米淀粉粘滞性谱和Mg、K等元素含量的影响最大,结实前期其次,结实后期的影响较小,开花后20 d内是稻米淀粉粘滞性谱和Mg、K等元素含量受温度影响的关键时期.Mg/K和Mg/(N·AC·K)与淀粉粘滞性谱特征值显著相关,可以作为稻米食味品质评价的参考指标.     

安宁河流域稻米生化品质与气候条件的关系

通过“合系39”在四川安宁河流域无控制的地理分期播种大田试验及稻米生化品质室内分析,定量研究了从穗前40d到成熟期各阶段气象条件对稻米生化品质的影响及关键时期,建立了稻米生化品质各组分与关键期平均温度、温度日较差和日照时数的综合关系模型．结果表明,气候生态条件对稻米生化品质各组分有重要影响,且不同组分的影响形式和关键时期不同．其组分与气候生态因子最显著相关的时段或在齐穗前,或在齐穗后,或从齐穗前持续到齐穗后．该模型于2002～2003年应用在安宁河流域优质稻生产决策中．累计推广优质稻7．3×10^4hm^2,较2001年增加3．0×10^4hm^2,农民增收2亿元,促进了优质稻的迅速发展．     

灌浆期高温对水稻光合特性、内源激素和稻米品质的影响

以2个籼稻品种:温度钝感型品种K30和温度敏感型品种R21为材料,利用人工气候室控温,在水稻灌浆期设置高温(日均温度34.9℃)和适温(日均温度28.0℃)处理,测定不同灌浆时期(5,10,15,20,25d和30d)光合特性、内源激素含量及稻米品质的变化。结果表明,高温增强了K30的光合能力,K30高温处理净光合速率(Pn)在整个灌浆期都明显高于对照;R21在灌浆前期(5、10d和15d)高温处理与适温处理Pn差异不明显,在灌浆后期(20、25d和30d)高温处理Pn下降。高温增加了K30叶片和籽粒脱落酸(ABA)含量;而R21高温处理和适温处理叶片与籽粒ABA含量的对比不明显。高温处理对两个水稻品种叶片和籽粒赤霉素(GA3)与生长素(IAA)含量也有不同程度影响。高温胁迫降低稻米品质,但K30比R21表现出更强的温度钝感特性。     

基于生态效应的水稻籽粒蛋白质含量预测模型研究

在中国、日本、泰国不同生态环境下进行多品种籼型和粳型水稻(Oryza sativa)的区域种植试验,通过分析水稻籽粒蛋白质含量与纬度、海拔、抽穗后温度和太阳辐射等气候生态因子的相互关系,确立了影响水稻籽粒蛋白质积累的主要气候生态因子函数,并使用权重系数来进一步修订各气候生态因子对水稻籽粒蛋白质的作用,构建出基于生态效应(主要气候生态因子函数)的水稻籽粒蛋白质含量预测模型。利用不同年份、不同生态点、不同品种类型的试验资料对所建模型进行了检验,籼稻和粳稻籽粒蛋白质含量的预测误差RMSE平均分别为0.27%和0.24%;籼稻试验点和粳稻试验点的预测误差平均为0.25%和0.22%,表明模型总体上具有较好的预测性和实用性。     

稻麦两熟地区机插水稻品质形成的播期效应

合理播期是机插稻实现高产、优质稻米生产的关键技术。本文研究了播期对粳型超级稻和籼粳交水稻机插方式下稻米品质形成特征的影响,为机插稻高产、优质稻米生产提供依据。结果表明:稻米糙米率、精米率、整精米率随播期推迟而升高,碾米品质变优,但早播稻糙米产量、精米产量、整精米产量显著高于晚播稻(P0.05);不同播期的稻米垩白粒率、垩白度变异较大,均随播期推迟而下降,早播与晚播间差异达显著水平(P0.05);外观品质改善,推迟播期,稻米直链淀粉含量降低,胶稠度变短,峰值黏度、热浆黏度、最终黏度、崩解值呈规律性下降,消减值变化幅度较大,逐渐升高,糊化温度波动较小,RVA谱变劣,稻米蒸煮食味品质变差;稻米蛋白质含量及蛋白质产量均随播期推迟而下降(P0.05),营养品质变差;机插粳稻适期早播,易取得高的糙米、精米、整精米及蛋白质产量,提升营养品质及蒸煮食味品质,改善米粉RVA谱特征,但降低稻米碾米品质和外观品质。因此,麦茬机插稻于5月26—31日播种,是实现较优品质稻米较高产量的最佳时期。     

我国6ka BP植被变化的气候模拟研究

根据花粉恢复的古植被表面中国森林区的常绿阔叶,和叶阔叶林以及针叶林在6Ka BP向北扩张,反映了6ka BP夏季和冬季均比现代温暖的气候特征,然而,根据地球轨道参数变化驱动的气候模式,由于6kaBP时北半球夏季太阳辐射高于现代,而冬季太阳辐射低于现代,模拟的6ka BP夏季温度比规划温暖,但冬季比现代寒冷,模拟得出的冬季寒冷与地 冬季增温不一致,说明6ka BP的气候和植被变化并不完全受到太阳辐射变化的控制,针对这一重大缺陷,我们利用具有陆面过程的全球大气环流模型（ACCM＋SsiB),采用了外动力太阳辐射变化和古地表状史的强迫边界场进行了古气候模拟试验,模拟结果能够捕捉到亚洲季风地区6kaBP冬季气候变暖的气候特征,初步阐明6ka BP植被变化的气候动力学机制。     

我国南北气候过渡地区稻米品质的地域分布

本文依据农业气候指标,运用模糊综合评判和定性聚类的方法,综合评价了所研究地区影响稻米品质的生态气候因子,并把该地区分为4个区域和9个亚区域,每个亚区的生态气候条件和稻米品质各有特色,且所有区域稻米品质变化具有共同的规律性.     

稻米垩白形成的气象生态基础研究

在全国13个点、19个品种多播期试验基础上,对稻米垩自形成的气象生态基础进行了分析。结果表明,水稻齐穗后15天的日均温是影响稻米垩白大小的主要气象因子。经对稻米垩白与齐穗后15天内均温关系的动态分析可知,稻米垩白随该时段温度提高而增大的拐点温度约为29℃(品种间略有差异),接近或超过该点温度,稻米垩白会突发性地增加。     

中国东部花粉比值与气候的关系及其在定量古气候重建中的应用

在中国东部连续的尘土孢粉样基础上,用转换函数的方法研究中国东部孢粉与气候的定量关系,研究结果证明,中国东部现代花粉的分布与年均温有密切关系,某些草本植物花粉之间的含量变化很大程度上与太阳辐射量和不同纬度的温度变化有关,因此定量重建古植被带的迁移及古气候的变化就成为可能,通过对比,选择Artemisisa与Poaceae的比值作为温度替代指标,Arte/Poac与纬度相关系数的平方值（R2）为0．9579,它与年均温的相关系数平方值也达到0．9162,用回归方程定量重建了中国东部海域钻孔DGKS－9602的古气候,由于末次盛冰期草本植物花粉丰富,获得的气候值可信度最好,即年均温比现代降低了8℃左右（6－10℃）,植被带向南推移了约8－10纬度,这一结果与前人的研究结果基本吻合。     

稻米蒸煮营养品质性状的遗传研究进展

稻米品质越来越成为我国稻米市场的决定因素。本对包括稻米直链淀粉含量、糊化温度、胶稠度、蛋白质含量和氨基酸的遗传,以及对上述品质性状间及其与某些农艺性状间的相关性进行了综述。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various