鹅膏属种群分布格局研究

采用方差／均值比率法测定了鹅膏属种群的分布格局类型。结果表明，47个鹅膏属种群，有1／4属于集群分布类型，有3／4属于随机分布类型。随机分布的种群其聚集强度指标扩散型指数、丛生指数、聚块性指标和平均拥挤度多对1．0没有显著的偏离，负二项参数则较大；而聚集分布的种群其聚集强度指标则符合聚集特征。     

DNA and morphological diversity of selected Greek tomato (Solanum lycopersicum L.) landraces

Utilizing inter-simple sequence repeats (ISSRs), the genetic diversity of 33 Greek tomato (Solanum lycopersicum L.) landraces and three cultivars, three cherry tomato (S. lycopersicum var.cerasiforme) cultivars and two accessions of Solanum pimpinellifolium L. was studied. Furthermore, 12 ISSR primers were also used to identify 27 morphotypes derived from 7 landraces. Based on Jaccard's coefficient, an average genetic similarity of 0.797 (ranged from 0.56 to 0.95) was found among the accessions. Cluster analysis using the UPGMA method placed all tomato landraces and cultivars into a single group, while the cherry hybrids and the S. pimpinellifolium accessions were placed in a second group. The ISSR data distinguished all the 27 morphotypes from each other and grouped the morphotypes derived from the same landrace together. The ISSR technology proved useful in describing genetic diversity among Greek tomato landraces and was capable of distinguishing the closely related morphotypes.     

Corridors and connectivity: when use and function do not equate

Connectivity, or the integration of populations into a single demographic unit, is an often desired, but largely untested aspect of wildlife corridors. Using a corridor system that was established at least 85 years prior, we investigated the extent of connectivity provided. This was undertaken using a combined ecological and genetic approach with connectivity estimated by gene flow. Vegetation within the corridor was found to be comparable in physical structure and species composition to that within the connected patches and the two target species (Melomys cervinipes and Uromys caudimaculatus) were shown to occur along the corridor but not within the surrounding matrix. These factors indicated that the corridor was suitable for use as a model system. The population structure (weights of individuals, sex ratios and the percentage of juveniles) of both species were also similar within the corridor and the connected patches suggesting that the corridor provided the resources necessary to sustain breeding populations along its length. Despite this, populations in patches linked by the corridor were found to show the same significant levels of genetic differentiation as those in isolated habitats. M. cervinipes, but not U. caudimaculatus, also showed population differentiation within the continuous habitat. Although based on only one corridor system, these results clearly demonstrate that connectivity between connected populations will not always be achieved by the construction or retention of a corridor and that connectivity cannot be inferred solely from the presence of individuals, or breeding populations, within the corridor. C. Wilson: deceased     

贮藏年限对不同居群白羊草种胚线粒体抗氧化性能的影响

为探讨贮藏年限对不同居群白羊草(Bothriochloa ischaemum)种胚线粒体抗氧化功能的影响,试验以贮藏1～4年的代县、平鲁、平定、柳林及太谷居群白羊草种子为材料,分析其种胚线粒体丙二醛(Malondialdehyde, MDA)含量及超氧化物歧化酶(Superoxide dismutase, SOD)、过氧化氢酶(Catalase, CAT)、抗坏血酸过氧化物酶(Ascorbate peroxidase, APX)和谷胱甘肽还原酶(Glutathione reductase, GR)活性的变化规律。结果表明：各居群白羊草种胚线粒体的抗氧化能力与其贮藏年限关系密切。随着贮藏年限的延长,白羊草种胚线粒体SOD,CAT,APX及GR活性逐渐降低,而其MDA含量逐渐升高。不同居群白羊草种子的耐贮藏性存在差异,太谷居群白羊草种子的贮藏年限可为3年,而代县、平鲁、平定及柳林居群白羊草种子的贮藏年限最好为1年。     

小桐子居群种子表型变异研究

对小桐子8个居群种子表型进行研究,测量种子长度、宽度、重量等11项形态学指标。种子表型性状,居群间的变异系数c.v.%=10.64~19.33,表型频率分化系数平均Pst=10.02%,表型方差分化系数平均Vst=14.27%,表明小桐子种子表型居群内变异是其变异的主要来源。居群间欧氏距离Q-聚类分析表明,种子表型分化基本与居群间的地理距离远近相关联。11个表型性状间多数呈极显著或显著的正相关,种子长度、宽、厚、周长和种子百粒重为小桐子易测定和重要的表型性状。     

不同品质类型小麦优质高产群体氮效率的差异

为给小麦分类栽培措施的确定提供依据,于2000～2002年在扬州选用5个不同品质类型小麦品种,通过不同类型小麦氮肥运筹调控试验,研究了小麦优质高产群体与普通群体的氮效率差异.结果表明,同一品种不同群体类型间氮肥农学效率、氮肥吸收效率表现为强筋和中筋小麦优质高产群体高于普通群体,而弱筋小麦优质高产群体略低于普通群体;氮素利用效率则表现为强筋小麦优质高产群体低于普通群体,中筋小麦两者之间相近,弱筋小麦优质高产群体高于普通群体;不同群体的氮收获指数差异表现为优质高产群体与普通群体相比互有高低;不同类型专用小麦的各氮效率指标与籽粒产量及蛋白质含量之间表现出不同的相关性.     

白羊草种群繁殖的数量特征

于抽穗-开花期测定分析白羊草(Bothrioch loaischaemum)株丛的繁殖数量特征。结果表明:丛茎枝数、丛地上生物量和丛生殖枝数分别随丛径呈指数函数增加,丛生殖枝重随丛径呈幂函数增加,丛地上生物量与丛茎枝数,以及丛生殖枝重与丛生殖枝数之间均呈线性增加,生殖枝数和营养枝数比值随株丛高度和丛径均呈二次曲线变化。     

Mycorrhizae,biocides, and biocontrol. 4. Response of a mixed culture of arbuscular mycorrhizal fungi and host plant to three fungicides

The effects of three commonly used fungicides on the colonization and sporulation by a mixture of three arbuscular mycorrhizal (AM) fungi consisting of Glomus etunicatum (Becker & Gerd.), Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, and Gigaspora rosea (Nicol. & Schenck) in symbiosis with pea plants and the resulting response of the host-plant were examined. Benomyl, PCNB, and captan were applied as soil drenches at a rate of 20 mg active ingredient kg^-1 soil 2 weeks after transplanting pea seedlings in a silty clay-loam soil containing the mixed inocula of AM fungi (AM plants). Effects of fungicides were compared to untreated plants that were inoculated with fungi (AM control). The effect of mycorrhizal inoculation on plant growth was also examined by including nonmycorrhizal, non-fungicide-treated plants (non-AM control). Fungicides or inoculation with AM fungi had only a small effect on the final shoot weights of pea plants, but had greater effects on root length and seed yield. AM control plants had higher seed yields and lower root lengths than the corresponding non-AM plants, and the fungicide-treated AM plants had intermediate yields and root lengths. Seed N and P contents were likewise highest in AM control plants, lowest in non-AM plants, and intermediate in fungicide-treated AM plants. All three fungicides depressed the proportion (%) of root length colonized by AM fungi, but these differences did not translate to reductions in the total root length that was colonized, since roots were longer in the fungicide-treated AM plants. Pea plants apparently compensated for the reduction in AM-fungal metabolism due to fungicides by increasing root growth. Fungicides affected the population of the three fungi as determined by sporulation at the final harvest. Captan significantly reduced the number, relative abundance, and relative volume of G. rosea spores in the final population relative to the controls. The relative volume of G. etunicatum spores was greater in all the fungicide-treated soils, while G. mosseae relative volumes were only greater in the captan-treated soil. These findings show that fungicides can alter the species composition of an AM-fungal community. The results also show that AM fungi can increase seed yield without enhancing the vegetative shoot growth of host plants.     

河南省狗牙根种质资源表型遗传多样性研究

基于7个表型性状对河南省自然分布的15个狗牙根居群的表型遗传变异及其与环境因子的关系进行研究,结果表明狗牙根供试性状总的变异系数从大到小依次为草层高度(40.18％)>匍匐茎叶长(36.46％)>节间长(33.20％)>直立茎叶长(32.77％)>匍匐茎叶宽(31.81％)>直立茎叶宽(28.57％)>节间直径(27....     

玉米杂种优势类群和模式的研究Ⅱ玉米自交系优势类群的划分和优势模式初探

以１５个来源不同的玉米自交余组成１０５个杂交组合为材料，初步研究了玉米自交系杂优类群的划分和利用模式的构建。根据杂种优势和配合力的测定结果，比较分析了被测自交系之间的遗传差异，将其划分为唐四、旅、Ｌａｎ、Ｒｅｉｄ、ＲＬ５大优势类群。不同类群间自交系之间的杂种优势和配合力存在着明显差异。对类群间可能组成的杂优利用模式的优劣进行比较，说明国内系×国内系、国内系×国内系和国内外系间的混合利用模式均可利用。