新疆北部为害胡杨的三种木虱形态识别及为害特征研究初探

[目的]查明为害新疆胡杨三种木虱的形态及为害特征,为研究其生物学特性和综合防控奠定基础.[方法]在胡杨林区定期定点观察和普查相结合,对采集的昆虫标本进行显微镜观察、鉴定.[结果]经过实地调查研究,初步确定了为害胡杨的木虱有三种,即蔡氏胡杨个木虱(Egeirotrioza ceardi)、纤细真胡杨个木虱(Evegeirotrioza gracilis)和无斑滑头木虱(Homalocephala uncolor).[结论]三种胡杨的木虱,在胡杨树上混合发生.在同一棵胡杨树上可见三种木虱及为害状,只是为害时间有所差异.蔡氏胡杨个木虱发生最早,其次为无斑滑头木虱和纤细真胡杨个木虱,无斑滑头木虱的若虫为害时间早于纤细真胡杨个木虱.     

环境因子对纤细角毛藻种群增长的影响

通过对纤细角毛藻的单种培养,研究了N、P、N/P和Si对其种群增长的影响.试验结果表明,纤细角毛藻的最适生长条件为:N、P质量浓度分别为5 mg/L和1 mg/L、N/P为8∶1、Si为4 mg/L.其中N/P是影响纤细角毛藻细胞生长的关键因素,纤细角毛藻细胞生长的速率主要取决于P所占比例的高低;Si浓度的变化对纤细角毛藻细胞增长的影响不明显(P>0.05),表明Si不是纤细角毛藻细胞生长的限制因子.     

Gracilaria gracilis (Gracilariales,Rhodophyta) from Dakhla (Southern Moroccan Atlantic Coast) as Source of Agar: Content,Chemical Characteristics,and Gelling Properties

Agar is a sulfated polysaccharide extracted from certain marine red algae, and its gel properties depend on the seaweed source and extraction conditions. In the present study, the seaweed Gracilaria gracilis (Gracilariales, Rhodophyta) from Dakhla (Moroccan Atlantic Coast) was investigated for its agar content, structure, and gel properties. The agar yields of G. gracilis were 20.5% and 15.6% from alkaline pretreatment and native extraction, respectively. Agar with alkaline pretreatment showed a better gelling property supported by higher gel strength (377 g·cm⁻²), gelling (35.4 °C), and melting (82.1 °C) temperatures with a notable increase in 3,6-anhydro-galactose (11.85%) and decrease in sulphate (0.32%) contents. The sulfate falling subsequent to alkaline pretreatment was verified through FT-IR spectroscopy. The ¹³C NMR spectroscopy showed that alkaline-pretreated agar has a typical unsubstituted agar pattern. However, native agar had a partially methylated agarose structure. Overall, this study suggested the possibility of the exploitation of G. gracilis to produce a fine-quality agar. Yet, further investigation may need to determine the seasonal variability of this biopolymer according to the life cycle of G. gracilis.     

Potential of parasitoids to control populations of the weevil Ceutorhynchus obstrictus (Marsham) on winter oilseed rape

Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae) is a major pest of oilseed rape in Europe and North America. The last decade has seen growing interest in the occurrence, importance and efficiacy of its parasitoids as biocontrol agents. The infestation of pods by C. obstrictus larvae and their parasitism rates were assessed in a total of nine commercially-grown crops and fifteen experimental plots of winter oilseed rape in 2004–2007. Pod samples were collected at the pod maturation stage and incubated in emergence traps. Emerged larvae, their exit holes and parasitoids were counted and identified; the percentage of infested pods and parasitism rates were calculated. Pod infestation by larvae increased continuously over the study period. The parasitism level was lowest in 2005 and increased thereafter up to 96%. The most abundant parasitoid was Trichomalus perfectus (Walker), but Mesopolobus morys (Walker) and Stenomalina gracilis (Walker) (Hymenoptera: Pteromalidae) were also reared from host larvae. This study showed that naturally-occurring ectoparasitoids of C. obstrictus were capable of becoming established as viable populations and have the potential to contribute to biological control of C. obstrictus.     

迷果芹不同密度播种试验

设计4种不同播种密度试验,通过迷果芹不同播种密度出苗率、两年生保苗率和生产量的对比分析,结果表明播种密度在15kg/hm2时收益最佳,人工栽培与野生药材的活性成分含量相差不大。     

对数级数模型在小叶青冈林物种多度格局研究中的应用

运用对数级数分布模型对福建茫荡山自然保护区小叶青冈天然林乔木层物种多度进行预测与检验,结果表明天然小叶青冈林乔木层物种多度分布基本符合对数级数分布,说明该小叶青冈林为发育成熟的群落,具有较大的稳定性和生物多样性。     

大豆种间的核型分析

通过对大豆3个种的核型分析,结果表明:(1)大豆体细胞染色体数均为2n=40;(2)3个种都只有1对位于最长染色体上的随体,而且随体染色体形态相近,都是近中部或近端部着丝粒染色体;(3)种间染色体长度及着丝粒位置呈规律性变化;(4)野生大豆的核型较不对称,其次为半野生大豆,而栽培大豆核型比较对称.     

磷浓度对盐生杜氏藻和纤细角毛藻叶绿素荧光特性及生长的影响

在温度(23±1)℃,盐度31,光照度5000 lx的条件下,用含有不同磷浓度(0、2.27、18.15、36.3、72.6、290.4μmol/L)的培养基对盐生杜氏藻和纤细角毛藻进行培养,研究2种微藻在一次性培养过程中,不同磷浓度对其PSII最大光能转化效率(Fv/Fm)、叶绿素含量以及细胞密度的影响。单因子方差分析结果表明,在整个培养周期中,磷浓度对两种微藻的光合作用及生长均有显著影响(P<0.05)。盐生杜氏藻的PSII最大光能转化效率、叶绿素含量以及细胞密度均随着起始磷浓度的增加而增加,在290.4μmol/L处达到最大值;纤细角毛藻的PSII最大光能转化效率、叶绿素含量以及细胞密度在18.15μmol/L处达到最大值,而后随着磷浓度的继续升高,其上述指标反而降低。所以盐生杜氏藻和纤细角毛藻进行光合作用和生长的最适磷浓度分别为290.4μmol/L和18.15μmol/L。     

栽培大豆、半野生大豆、野生大豆比较胚胎学研究

通过对栽培大豆、半野生大豆和野生大豆比较胚胎学研究,指出了三种类型大豆具有相同的胚胎学发育特征,这些特征如下:1.雄性孢原为表皮下多细胞;小孢子母细胞减数分裂的胞质分裂为同时型;四分孢子主要为正四面体形,少数为左右对称形;成熟花粉粒为二细胞型;花药壁的发育属基本型;绒毡层细胞单核,属分泌型绒毡层。2.单室子房;弯生胚珠,双珠被,厚珠心;胚珠亚表皮下多孢原;多数大孢子四分体线形排列;少数为“T”字形排列,合点端大孢子有功能;胚囊发育为蓼型,反足细胞短命。3.大孢子发生较小孢子发生稍晚,但发育速度较快,后期雌、雄配子体同步成熟。4.自花授粉;受精过程属有丝分裂前配子融合类型。5.胚的发育属柳叶菜型;核型胚乳,胚乳发育中后期胚囊合点端存在胚乳吸器;胚珠合点端具承珠盘结构。     

大豆种间杂交后代数种农艺性状的遗传力与遗传进度的估算及其应用

本文研究了大豆种间杂交(G. max×G. gracilis, G. max×G. soja)后代的遗传力、遗传进度。结果表明:种间杂交后代主要农艺性状的遗传规律基本上与栽培种内品种间杂交相类似,可利用类似于处理栽培品种杂交后代的方法处理种间杂交后代;种间杂交后代的遗传进度较大,选择效应明显。