土壤外源钴对大麦根伸长的毒害及其预测模型

选取我国11种不同性质的农田土壤,通过外源添加重金属钴（Co）,研究其对大麦（Hordeum vulgare L.）根伸长的毒性阈值及土壤性质对Co毒性的影响。结果发现,Co对大麦根伸长10%抑制效应（EC₁₀）在11种土壤中的变化范围为37.1~3 914 mg·kg^-1土（105.5倍）,50%抑制效应（EC₅₀）的变化范围为166.1~6 030 mg·kg^-1土（36.3倍）。建立土壤性质与毒性阈值的回归方程,结果表明土壤pH是影响土壤Co毒性阈值最重要的因子,作为单因子时分别可以解释77.6%、72%的EC₁₀和EC₅₀的变异（P≤0.001）。当在EC₁₀预测模型中引入土壤pH和土壤黏粒（Clay）双因子时,可以解释83.9%的EC₁₀的变异（P<0.001）,EC₅₀预测模型中引入土壤pH和总碳（TC）双因子时,可以解释86.1%的EC₅₀的变异（P<0.001）。将我国土壤中得到的Co毒性阈值预测模型和欧洲北美10种土壤的预测模型进行比较验证,结果发现基于我国土壤得到的预测模型可以较为准确地预测欧洲北美土壤中Co的大麦根伸长毒性阈值,但基于欧洲北美土壤的预测模型不能准确预测我国土壤中Co的毒性阈值。研究表明,我国土壤性质对Co毒性有显著的影响,基于土壤性质建立的预测模型可为土壤中Co生态风险评价提供参考依据。     

桑小头木虱Paurocephala sauteri Enderlein生物学特性研究

近年在海南各植桑区均发现桑小头木虱（Paurocephala sauteri Enderlein）严重为害,桑园被害株率达100%。在我国,该木虱仅记录于台湾省,为我国大陆新入侵害虫。本研究在实验室条件下[(27±1)℃、RH (70±5)%、12L∶12D],采用45日龄桑树扦插苗和离体叶片饲养,对桑小头木虱的发育与繁殖特性及各虫态的形态特征开展观察。结果表明,桑小头木虱生活史包括卵、1~5龄若虫和成虫期。各龄期主要形态特征为：卵呈水滴形,带短的卵柄,端部具细长的端丝,初产时乳白色,待孵化时可见淡红色眼点;1龄若虫头、胸部乳白色,复眼和腹部橘黄色,无翅芽;2~5龄若虫黄绿色,随着龄期增加,体长增加,翅芽随之变化。2龄翅芽出现,稍突起;3龄翅芽较小,呈三角形;4龄和5龄翅芽长椭圆形,其中5龄超过腹部第1节。各龄若虫和初羽化成虫均可分泌白色球形蜡质。雌雄成虫以两性生殖方式繁殖后代,羽化3 d后体色由黄绿色逐渐变为黄褐色并开始交配,交配时间为0.5~3 h,结束交配18~21 h后开始产卵,产卵量为20~42粒。卵单个散产于叶片背面叶脉处,偶尔可见产于新抽嫩叶正面边缘,5~7 d后孵化,孵化率为98.19%,雌性百分率为70.44%。若虫期12~18 d,完成一代的时间为18~24 d。本研究将为桑小头木虱的准确识别与监测,以及防控策略的制定提供前提条件和理论依据。     

Abnormal development of genital organs in offspring male mice exposed to finasteride during pregnancy

AIM: To investigate the effects of finasteride exposure during pregnancy on the development of reproductive organs in offspring male mice. METHODS: CD-1 mice were treated with finasteride from 0 to 17 d after conception. The development of reproductive organs in the offspring male mice were observed by macroscopy, anatomical analysis and histological staining. The spermatogenesis was analyzed by immunofluorescence staining. RESULTS: Macroscopic observation showed that fenasteride exposure during pregnancy resulted in external genital malformations in the offspring male mice, which were manifested as incomplete scrotal fusion and penile malformation. In addition, the anogenital distance was significantly shortened (P<0.01). Histological staining showed that the length of penis at each stage was significantly shortened (P<0.01), the density of seminiferous tubules in testis and mature spermatozoa in seminiferous tubules were significantly decreased (P<0.01), and the luminal space size of seminiferous tubules and interstitial space size of testises were significantly increased (P<0.01). Immunofluorescence staining showed that the densities of Sertoli cells, Leydig cells and spermatogonium in testis were significantly reduced (P<0.01), and the fluorescence intensity of caspase-3 in spermatogenic tubule cells was increased significantly (P<0.01). However, the fluorescence intensity of Ki67 and desert hedgehog (Dhh) was decreased significantly (P<0.01). CONCLUSION: Finasteride exposure during pregnancy results in abnormal development of reproductive organs in offspring male mice and affects spermatogenesis.     

Projecting the suitability of global and local habitats for myrtle rust (Austropuccinia psidii) using model consensus

Myrtle rust (caused by Austropuccinia psidii) affects more than 500 known host species in the Myrtaceae family. Three different modelling approaches (CLIMEX, MaxEnt and Multi-Model Framework) were used to project the habitat suitability for myrtle rust at both global and local scales. Current data on the global occurrence of myrtle rust were collected from online literature and expert solicitation. Long-term averages of climate data (1960–1990) were sourced from WorldClim and CliMond websites. Recent reports of myrtle rust in New Zealand were used for validation of model outputs but not in model training and testing. The model outputs were combined into a consensus model to identify localities projected to be suitable for myrtle rust according to two or three models (hotspots). In addition to the locations where the pathogen is currently present, all models successfully projected independent occurrence data in New Zealand suitable for establishment of the pathogen. Climate suitability for the pathogen was primarily related to temperature followed by rainfall in MaxEnt and the CLIMEX model. The results confirmed the optimum temperature range of this pathogen in the literature (15–25 °C). Additional analysis of the precipitation variables indicated that excessive rain (more than 2000 mm in warmest quarter of the year) combined with high temperatures (>30 °C) constrain pathogen establishment. The results of the current study can be useful for countries such as New Zealand, China, South Africa and Singapore where the pathogen has not fully spread or established.     

不同灌溉模式下光合有效辐射与水稻叶片水分利用效率关系研究

根据江西省示范区晚稻节水灌溉试验资料,研究了不同灌溉模式下叶片水分利用效率随光合有效辐射的变化规律,分析了光合有效辐射与叶片水分利用效率的主要影响因子,气孔导度、胞间CO2浓度以及叶气温差的关系。结果表明:水稻叶片水分利用效率随光合有效辐射的增大表现出先增大后下降的变化趋势,二者之间表现出较好的二次曲线关系;光合有效辐射在500~900μmol/(m2.s)范围内,叶片水分利用效率均大于7.0μmolCO2/mmolH2O;控制灌溉模式下,水稻叶片水分利用效率略大于常规灌溉模式下的单叶水分利用效率,但无明显差异;光合有效辐射与气孔导度、胞间CO2浓度之间表现出较好的多项式关系,与叶气温差呈明显的直线关系,它们的关系从一定程度上揭示了光合有效辐射影响水稻叶片水分利用效率的生理机制。     

邵东县水田种植制度优化模型的研究

本文应用线性规划原理,建立了湖南中部丘陵地区邵东县水田种植制度优化模型。优化过程中,以净产值(不包括利息和税金)为目标函数,对总面积、主要作物播种面积、适宜用地、冬闲田等进行了约束。优化结果净产值可增加17801900元,增长了14.4%。     

杉木和马尾松幼林生物产量模型研究

本文在对6年生杉木和马尾松标准木调查的基础上,应用相关分析方法,找出杉木和马尾松幼林各器官生物量与树高、胸径之间的相关关系。应用Y=aD~b和Y=aD~bH~c数学模型建立了杉木和马尾松各器官生物量的估测数学模型。其中以Y=aD~bH~c的数学模型为最佳,可作为一定立地条件下的杉木和马尾松幼林的生物产量估测。     

鲢滤食器官胚后发育生物学的研究

通过显微解剖、肉眼解剖、石蜡切片、光镜和扫描电镜观察等方法,系统观测全长5～395mm鲢标本730多尾,描述了鲢鳃耙和鳃耙网、腭褶、鳃耙管等滤食器官的形态学特点和数量性状在胚后发育过程中的变化规律;论述了鲢滤食器官发育与摄食方式的转化、摄食器官的数量性状发育与适口食物和食物组成的转变、鳃耙间距在胚后发育过程中的变化、鳃耙管的功能、鲢对食物的选择性、鲢滤食器官发育与苗种培育阶段的划分和饲养生物学技术措施。为制定培育鲢苗种和饲养食用鱼生物学技术措施提供了理论依据。     

大庆城市湿地水生生态系统重金属转移模型研究

该文以大庆城市湿地北二十里泡为例,研究生活污水污染泡沼重金属分布及转移规律,为进行湿地环境影响评价和治理湿地水生生态系统重金属污染提供理论依据.通过对该湿地中水、沉积物及芦苇体内重金属含量的分析测定,并采用方差分析、线性和非线性模拟对试验数据进行统计和模型拟合,结果表明:①水样、底泥、植物根部、茎叶中重金属分布趋势与对照无显著差异,但含量均明显高于对照.②不同部位水样、底泥、植物根部、茎叶中的重金属种类及含量明显有差异.不同重金属与底泥的键合能力不同,铅和镉的键合能力最强,最容易在底泥中沉积.芦苇对汞和铅的转移能力最强,而对铜和锌的富集能力最强.③重金属在转移链中具有明显的转移规律,铜、锌、铅等具有较好的转移模型,多呈多项式和反比例函数关系模型.该研究主要基于统计学的原理,提出了生活污染泡沼水—底泥—根系—茎叶之间的转移模型,模型均通过小概率检验,精度较高,具有一定的实用性.     

茶树树冠结构变化的数学模型研究

为对不同树龄茶树的树冠结构进行科学评价,并为制定合理的农业技术措施提供依据,以小乔木型品种福鼎大白茶和灌木型品种槠叶齐为材料,对湖南8个地（市）规范化栽培茶园1～18年生两类品种茶树树冠结构的15项指标进行系统调查,并运用计算机作数据分析。结果表明,两类型品种树冠结构指标随树龄的增大呈现出基本一致的变化规律,各项树冠指标均可用一定的数学模型予以表达。研究结果还表明,两茶树品种在1～6年生期间,各项树冠指标增幅较大,7～14年生期间树冠指标的增加或减少的幅度不大,树冠结构比较稳定;14年生后,一些与茶叶品质和产量密切相关的指标,如新梢密度、生产枝密度、百芽重、一芽三叶长度和单叶面积下降幅度回大,同时,从两类型品种树冠结构指标的变化来看,茶树类型不同,树冠结构动态变化存在着差异。