海拔梯度对台江方竹发笋节律的影响研究

通过原产地对合江方竹不同海拔梯度发笋节律的观察和研究，得出其开始发笋期、停止发笋期及发笋数都随着海拔梯度的变化有显著或极显著的差异，海拔越高，发笋越早，停止发笋期也越早，平均发笋量3300株／667m^2。其发笋期可以划分为开始期、高峰期和停止期阶段。在海拔l200In以L开始发笋期出现在9月中旬，停止生长期出现在10月上旬；1000m以一卜开始发笋期、停止生长期分别出现在9月下旬和10月底以后；随着海拔高度平均每降低100m，开始发笋期推迟2—3d，停止发笋期随着海拔高度平均每降低100m推迟3—4d。数学模型（以9月13日为第一天），发笋开始期为K=31．333-0．02383H海拔，停止发笋期为T=64．867-0．03217H海拔；合江方竹在不同海拔梯度的发笋性状可以划分成900m以下和900m以上两类，其中900m以下具有“笋期晚发笋多（晚多）”特性；900m以上具有“笋期早发笋少（早少）”特性。     

Effect of mate selection on fuzzy selective mating criteria in closed dairy multiple ovulation and embryo transfer nucleus programs

In order to control rates of response and inbreeding, mate selection using fuzzy selective mating criteria (FMC) was investigated in adult multiple ovulation and embryo transfer nucleus schemes for dairy cattle. Stochastic simulation was used to model the closed nucleus scheme. This mate selection was examined in four alternative mating and male selection schemes: (i) a hierarchical scheme; (ii) a hierarchical sibship scheme (two males per sibship); (iii) a factorial scheme (two sires per dam); and (iv) a factorial sibship scheme (two males per sibship and two sires per dam). Genetic response and inbreeding rate tended to be reduced by increasing the trade-off parameter of FMC between the expected breeding value and inbreeding of progeny. Inbreeding rates in all schemes were reduced by reducing the variance of family size through selection and the average coancestry of mating pairs through mate allocation.     

The Biology of the Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

After about 25 years of intensive research a substantial moment of information has accumulated on the basic biology of Prostephanus truncatus in stored products. This article reviews the literature on the geographical distribution, biotypes, symbiotic associations, mating and flight behaviour, oviposition, and development on both agricultural and non-agricultural hosts. The current knowledge about the nutritional biology (including the role of symbionts) and host finding behaviour (including the inter-linked roles of plant chemicals and the insect's own pheronones) are highlighted as research areas which deserve future attention. In addition, few studies have been conducted to determine the extent to which the biology of P. truncatus permits it to survive and reproduce in non-agricultural environments. These areas of study should be pursued as possible routes to providing more effective integrated pest managements strategies for the larger grain borer.     

Potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador

To determine the potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador, 13 A1 isolates belonging to clonal lineages US-1, EC-1 and EC-3, and 11 A2 isolates belonging to the clonal lineage EC-2, were paired on agar plates to induce crossing. In the first experiment, six A1 isolates (three US-1, two EC-1 and one EC-3) were each crossed with three A2 isolates (total = 18 crosses). Matings involving isolates of the EC-1 lineage produced more oospores of healthy appearance than did matings with isolates of US-1 or EC-3. In the second experiment, the oospores of 35 crosses (21 EC-1 × EC-2; 10 US-1 × EC-2; four EC-3 × EC-2) were dispersed on water agar to assess oospore germination. Overall, germination percentages were low. Only one cross produced enough progeny for evaluation. Twenty-three single-oospore offspring were isolated and evaluated for mating type; electrophoretic patterns of glucose-6-phosphate isomerase ( Gpi ) and peptidase ( Pep ) alloenzyme loci; mitochondrial DNA haplotype; and genomic DNA fingerprint. Multilocus genotype data indicated that all 23 isolates resulted from meiotic recombination. Four progeny with homothallic phenotype appeared to be unstable heterokaryons. Markers at several loci segregated according to simple Mendelian expectations for a diploid organism, but the ratios of three RFLP loci and the Pep locus were not consistent with Mendelian expectations. All progeny were nonpathogenic on hosts of the parental genotypes. Reduced mating success and reduced pathogenic fitness of progeny appear to be postmating mechanisms of reproductive isolation in populations of P. infestans sensu lato in Ecuador.     

Bt对小地考虑呼吸作用的影响

利用红外CO2分析仪测定小地老虎幼虫呼吸节律的变化结果显示：小地老虎幼虫呼吸节律属于不规则波动型，取食含Bt烟叶的幼虫呼出的CO2量显著低于对照组，且呼吸节律的波动性也明显增大，说明小地考虑幼虫取食Bt后，呼吸代谢受到一定干扰，出现呼吸水平降低及代谢紊乱现象。     

云南省马铃薯晚疫病菌的交配型、抗药性及生理小种分布的研究

 从云南省陆良县、建水县和南涧县采集2000年秋播的马铃薯晚疫病标本,分离获得124个致病疫霉菌株,连同1999~2000年分离自昆明、曲靖等地的春播马铃薯晚疫病的10个菌株共134个,采用常规技术对这些菌株进行了交配型、抗药性及生理小种的研究。交配型测定结果为:陆良县的18个菌株中有3个为A₂交配型,其余15个菌株为A₁交配型,建水县和南涧县的106个菌株及昆明、曲靖1999~2000年的10个菌株都是A₁交配型。测定了83个菌株对瑞毒霉(metalaxyl)和烯酰吗啉(dimethomorph)的抗药性,结果有12.0%的菌株对瑞毒霉表现抗性,16.9%表现中抗,71.1%表现敏感,其中陆良、昆明和曲靖的抗瑞毒霉菌株的比例大于建水和南涧的抗药性菌株的比例;所测定的83个菌株都对烯酰吗啉表现敏感。生理小种鉴定结果表明,云南晚疫病菌为3.4、0、3和4生理小种,分别占鉴定菌株总数的48.0%、32.5%、15.6%和3.9%。但南涧仅发现3.4和0小种,而昆明有0、3、3.4和4小种,陆良有0、3和3.4小种,可见昆明和陆良地区的晚疫病菌生理小种比南涧地区的生理小种的组成更趋多样。     

动物生物钟基因研究进展

昼夜节律生物钟是一种以近似24小时为周期的自主维持的振荡器,由输人通路、中央振荡器和输出通路三部分组成的。生物钟机制的研究已深入到分子水平。生物钟相关基因相继被分离鉴定,它们及其编码的蛋白质产物构成的自主调节的转录和翻译反馈环是生物钟运转的分子机制。本文介绍了果蝇和小鼠主要生物钟基因的发现以及其突变体对生物昼夜节律的影响,展望了揭示生物钟调节机制在遗传学上的重要意义。     

天然更新伯乐树的生长过程初步分析

解析1株天然林中148年生伯乐树倒木树干，表明其树高连年生长量在65年生时达到最大值，和树高年平均生长量曲线相交于80年生时；胸径连年生长量在70年生时达到最大值，与胸径年平均生长量相交于95-100年生时；而材积连年生长量的最大值出现在80年生时，与材积年平均生长量于135-140年间相交，此时可以认为是伯乐树的材积数量成熟年龄。     

大麦杂种优势利用研究,Ⅲ.大麦异棱型和同棱型F1杂种的杂种优势特征

研究了大麦4种杂交类型（含二棱×二棱、二棱×六棱、六棱×二棱和六棱×六棱）的F₁杂种的性状表现和优势特征，比较了同棱型相配组（二棱×二棱和六棱×六棱）和异棱型相配组（二棱×六棱和六棱×二棱）的超高亲优势（H_h）组合数及其出现率。研究性状包括株高、穗长、穗下节间长、穗数、粒数、粒重、籽粒产量、籽粒蛋白质含量和赖氨酸含量等13个.结果表明,(1)二棱×二棱杂种的穗长较长、每株穗数较多、千粒重较高；六棱×六棱杂种的每穗粒数、每株粒数较多、籽粒产量较高；而异棱型相配杂种则比同棱型相配组有较高的株高、穗下节间长和千粒重。（2）4种杂交类型杂种的类型内杂种间变异，在大多数性状上均为同质，仅有株高、穗长和主穗粒数在六棱×六棱杂种中变异增大，有较大的选择潜力。（3）在13个数量性状中，有9个性状的H_h优势出现率与杂交类型显著关联；株高、穗下节间长和千粒重的H_h优势出现率在二棱×六棱和/或六棱×二棱杂种中最高，而主穗粒数、每穗粒数、每株粒数、每粒重和每株干重的H_h优势出现率则在六棱×六棱和/或六棱×二棱杂种中最高。（4）异棱型相配组杂种的株高、穗下节间长和千粒重的Hh优势率显著高于同棱型相配组杂种，依次为20/30对8/33、30/30对18/33和22/30对5/33；但同棱型相配组杂种籽粒产量的H_h优势率显著高于异棱型相配组杂种，为10/33对2/30。说明异棱型杂种易产生生物量和千粒重优势，而同棱型杂种易产生籽粒产量优势。     

生物节律对动物生理营养及物质消化利用调控的研究进展

生物钟是生物的计时机制,是生物体内的一种无形的“时钟”。实际上是生物体生命活动的内在节律性,是由生物体内的时间结构序列所决定,使行为、生理和新陈代谢的内部循环与外界环境周期性同步。本文就生物节律系统、生物钟的调控基因、生物钟对营养生理代谢和消化器官的调控以及其在实际生产中的应用作一综述。