60Co γ射线对续随子干种子的生理损伤

以1Gy/min的剂量率,用不同剂量（0~800Gy）的60Co γ射线辐照续随子干种子,对M₁种子萌发情况及苗期性状进行调查。分析结果显示,在供试剂量范围内,辐照对续随子发芽率无明显影响,对发芽势、发芽指数、活力指数及幼苗生长量有显著或极显著的抑制效应;且抑制效应随剂量的增加和幼苗的生长而增大。在以上数据分析的基础上,以活力指数下降一半时的脊梁VID₅₀及幼苗半致癌剂量GR₅₀为标准,通过回归分析初步预测,供试续随子适宜辐照诱变剂量约为400~600Gy.     

6个一品红品种对60Coγ辐照敏感性研究

采用10、20、30、40 Gy的60Co γ射线辐照6个一品红品种的扦插苗,观测各处理植株的成活率及植株生长情况,并进行回归模型分析。结果表明：辐照使一品红植株的生长受到抑制,并且剂量越高抑制效应越明显;植株的存活率、株高、叶长、叶宽、叶面积均与辐照剂量呈显著负相关;不同一品红品种的辐照敏感性存在差异,其半致死剂量为21.94 ~ 28.71 Gy。     

五指毛桃繁殖技术的研究进展

五指毛桃具有食用及药用价值,常用来煲汤或作为中药材治疗多种疾病。由于滥砍滥挖,野生资源逐渐枯竭,人们正寻求有效方法对其进行繁殖。简述五指毛桃种子繁殖、扦插繁殖和组织培养3种繁殖技术,以及田间管理和病虫害防治技术,以更好的保护和利用五指毛桃野生种质资源。     

The impact of cropping on weed species composition in rice after fallow across a hydrological gradient in west Africa

In a 5-year experiment, weed species composition in rice was recorded at different positions along the toposequence, from the rain-fed upland to the irrigated valley bottom. A total of 107 species was recorded, 70 of which occurred in more than 1% of the total of 465 samples. Canonical correspondence analysis was used to explore the changes in weed flora over time in the different rice-growing environments. There were substantial differences in the composition of weed flora between the differing environments and years. On the upland sites, there was a pronounced shift from perennial grasses, including Imperata cylindrica (L.) Raeuschel and Pennisetum purpureum Schum., to annual grass weeds, such as Digitaria horizontalis Willd., Chloris pilosa Schum. and Eleusine indica (L.) Gaertn. The forbs Boerhavia spp. and Euphorbia heterophylla L. also increased in abundance, whereas others, such as Aspilia bussei Hoffm. & Muschl. and Laggera aurita (L.f.) Sch. Bip. ex C. B. Clarke, declined. The total number of species in the upland site declined from 30 to 11 between 1992 and 1996 compared with 11 to eight species in the same period in the irrigated lowlands. Although the numbers of species recorded in the lowlands were lower and more stable over time, there was an increase in problem grass weeds, such as Echinochloa crus-pavonis (Kunth.) Schult. in the irrigated lowlands and Leersia hexandra Sw.in the rain-fed lowlands.     

The use of fomesafen for pre-emergence weed control in cotton

The herbicide fomesafen was found to be selective in preplanting and pre-emergence treatments in cotton (Gossypium hirsutum L.). It was effective due to residual soil activity in controlling some of the most troublesome weeds in cotton fields,i.e., pigweed (Amaranthus spp.), black nightshade (Solarium nigrum L.), velvetleaf (Abutilon theophrasti Medik.) and cocklebur (Xanthium spp.). The best soil activity of fomesafen was achieved from pre-emergence or preplanting applications which were activated when the soil was wetted by rain or sprinkler irrigation, but the herbicide caused damage to the crop’s foliage if rain fell just after the cotton emergence. The most effective and safest method for applying fomesafen in cotton fields was preplanting followed by mechanical incorporation to a depth of 10 cm. Combinations of fomesafen with trifluralin were effective and completed the spectrum of controlled weeds in cotton, including annual grasses, common purslane (Portulaca oleracea L.) and field bindweed (Convolvulus arvensis L.).     

遮荫对盆栽一品红光合特性及生长的影响

 研究了不同程度的遮荫(0, 50% , 75% ) 对一品红光合特性及生长的影响。结果表明, 一品红具有较高的光饱和点和较低的光补偿点, 是对光照强度适应能力较强的阳性植物, 但不同栽培品种对遮荫环境的适应性有较大差异。遮荫使一品红叶绿素含量增加, 叶色浓绿, 但降低光合速率, 减少叶片中可溶性糖和可溶性蛋白质含量, 抑制侧枝的生长, 使花头直径、红色苞叶面积减小, 苞叶花青素苷含量降低。     

Effect of matrix habitat on the spread of flea beetle introductions for biological control of leafy spurge

Matrix habitats are known to influence the movement patterns of a variety of species but it is less well known whether these effects have strong implications for spatial population dynamics, including the spread of biological introductions. Using a spatially explicit simulation model parameterized with empirical data, we examine how grass and shrub matrix habitats, each offering different resistance to dispersal, influence the spread and impact of a biocontrol agent, Aphthona lacertosa, on the invasive weed, leafy spurge. Model predictions indicate that differential responses to matrix habitat have little effect on the agent’s spread over the study landscape and this is supported by statistical models fit to observed A. lacertosa incidence on the same landscape. Subsequent experimentation with the simulation model suggested that A. lacertosa colonization rates were largely unaffected by increases in amount of the more restrictive shrub matrix. However, simulations of an hypothetical species with greater overall dispersal ability but reduced dispersal rate through shrub matrix showed that colonization rates were noticeably reduced when the percentage of shrub matrix on the landscape approached 50%. Combined these results suggest that some tailoring of release strategies may be required to accommodate the unique dispersal capabilities of different biocontrol agents on particular release landscapes, but for A. lacertosa there appears to be little effect of matrix habitat structure on rates of spread.     

Molluscicidal evaluation of three common plants from India

Mortality caused by the aqueous extract of latex of Thevetia peruviana, Alstonia scholaris and Euphorbia pulcherrima against two harmful freshwater snails, Lymnaea acuminata and Indoplanorbis exustus, is reported. Latices of all the plants at high doses were also lethal to freshwater fish Channa punctatus, which shares the habitat with these snails, but within 24 h, LC90 of snail L. acuminata did not cause any mortality to fishes in a mixed population of snail and fish. Therefore, these plant extracts may eventually be of great value for the control of harmful aquatic snails and other molluscan pests.     

桉树等植物吲哚乙酸氧化酶活性变化与插条生根的比较研究

对４种桉树和易生根的山指甲、一品红、福建茶插条吲哚乙酸氧化酶活性变化与生根的关系研究结果表明，容易生根的植物体内ＩＡＡ氧化酶活性较低，难生根的植物ＩＡＡ氧化酶活性都较高。同一植物枝条的不同切段，体内ＩＡＡ氧化酶活性差别较大，近顶端部分酶活性较低，离顶端较远的部分酶活性依次升高。各植物的ＩＡＡ氧化酶活性均表现季节性差异，不同植物有各自的表现规律。插条扦插后，体内的ＩＡＡ氧化酶活性有逐渐升高的趋势。本     

辽宁省野古草野生居群表型性状多样性研究

为揭示野古草野生居群的表型变异规律,采用变异系数、主成分分析和聚类分析方法对采自辽宁省的8个野古草居群的10项形态性状进行多样性分析。结果表明,这10个表型性状在居群间的差异均达到极显著水平,各性状特征在居群间存在广泛的变异,变异系数由大到小依次为小穗总数(42.01%)旗叶厚度(27.94%)旗叶长度(26.83%)旗叶宽度(20.98%)叶数(19.64%)茎基粗(19.70%)花序长(19.30%)单枝干重(18.62%)株高(10.19%)花序重(8.16%)。10个形态特征可归成为3个主成分因子,累计贡献率达到79.44%,最大程度上反映了所有材料的表型性状特征,不同种群之间的差异主要来源于花序长、花序干重、单枝干重、小穗总数。采用欧氏距离系统聚类法将8个野古草居群依据10个表型性状分为3类:株型高大,旗叶长而宽,生物量大;株高中等,茎基粗壮,旗叶长而窄,小穗数量多,生物量较大;植株矮,叶片短、窄,生物量最小。表型性状与地理因子的相关性分析表明,部分表型性状的变化与地理因子呈显著或极显著相关性。