龙须草居群间叶片光合性能参数分析

对取自广东、广西等9省20个县的20种龙须草居群叶片光合性能参数分析结果表明:龙须草叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO2浓度(Ci)和水分利用率不仅在居群间存在极显著差异,而且彼此间还存在不同程度和不同性质的相关性;按遗传距离为15,可将20种供试龙须草居群聚为4类.从高光效育种需求而言,处于第三类中的湖南慈利居群和湖北丹江居群是龙须草高光效育种可利用的最优良种质资源,其次为处于第二类中的湖北郧县居群和湖北郧西居群.     

多鳞四指马鲅4个地理群体的形态差异

针对多鳞四指马鲅（Eleutheronema rhadinum）群体分布广泛,种群结构不明等突出问题,本实验分别采集了来自江苏东部海域（QD）、广东湛江附近海域（ZJ）、上海崇明附近海域（CM）、海南琼海附近海域（QH）4个地理群体共计144个样本,借助多变量形态度量学方法对4个地理群体的形态变异进行了研究,为多鳞四指马鲅不同地理群体结构研究提供资料。本文对144个样本数据校正后进行聚类分析、主成分分析和判别分析比较了4个群体间的形态差异。聚类结果表明,4个群体分为两支,CM和QD群体欧式距离最为接近,聚为一类;ZJ和QH群体聚为一类。CM、QD群体和ZJ、QH群体亲缘关系较远。主成分分析结果显示,可量数据和框架数据共计32项形态参数中,后背部和头部特征对各群体间的差异贡献率最大。运用判别分析建立4个群体的判别函数,其综合判别准确率为87.4%。分析结果显示多鳞四指马鲅4个地理群体在形态上已产生了一定程度的差异。     

3种不同类型棉田害虫与天敌时空动态变化

[目的]为建立转基因棉田害虫的综合防治体系、合理保护和利用天敌和转基因棉的环境安全性评价提供一定的理论和实践依据。[方法]对3种不同类型棉田(转双价棉、转Bt棉和常规棉田)害虫和天敌种群的时空动态进行研究。[结果]3种类型棉田的害虫和捕食性天敌的种类基本相同,但数量差异较大。双价棉田害虫561头/百株,Bt棉田害虫589头/百株,常规棉田害虫1 018头/百株。不同时期害虫和天敌优势种类不同,害虫和天敌种群呈现有规律的时空变化,转双价棉田与转Bt棉田差异不显著,转基因棉田与常规棉田的差异达到显著水平。[结论]转基因棉对害虫有明显抗性。群落特征指数分析表明,转基因棉田群落稳定性高于常规棉田,群落稳定性随棉花生长期呈现规律性变化。     

36份新疆野生黄花苜蓿SSR水平的差异性研究

以36份新疆野生黄花苜蓿为材料,采用SSR分子标记对其遗传多样性进行分析,以期为新疆黄花苜蓿资源评价和核心种质库构建提供基础数据.结果表明,9对SSR分子标记引物PCR共扩增出93条条带,每对引物扩增出的条带数变异范围为3～19条,平均10.33条/对,多态条带总数为86个,多态条带百分比为92.47％,平均多态性条带...     

Computer-simulated evaluation of insect phenology models developed in the tropics: Chilo suppressalis (Walker) as an example

For beneficial insects--predators and parasitoids--to be used effectively within pest control scenarios, it is often necessary to have fundamental as well as more applied information about them, including data on population dynamics, host switching and breeding systems. In recent years, such information has been gained by the use of molecular DNA markers. In this article, we briefly discuss the range of molecular markers available and their potential uses, concentrating on how particular markers have been employed to unravel different patterns of behaviour. Whilst alternative methods of tracking insects have proved highly informative when applied over small geographical scales (e.g., fluorescent dyes and radar transponders as attached to bees, etc), these approaches tend to be confined to studies of movement rather than other potentially important behaviours.     

Collection and characterization of naturalized populations of white clover (Trifolium repens L.) in Argentina

A collection formed from 53 accessions of white clover stolonswas carried out in naturalized populations from Argentina betweenparallels 26° and 37° South latitudes and 58° to 62°West longitude. Almost half of them (43%) wereobtained from grazed sites. Collected samples were grown in the fieldat Pergamino Experimental Station and compared with a local cultivar.Attributes scored or measured were petiole length, width and lengthof central leaflet, relation width/length, height, growing habit,leaf mark, stolon thickness and density, days to flowering,cyanogenesis, seed yield and winter herbage yield. There weresignificant correlations among seven pairs of characters. Allpopulations were cyanogenic within a range from 40 to 100%.Populations from grazed sites had prostrate habit and lower canopyheight than those from non grazed sites. The collection was clusteredin seven groups. Differences among groups were attributed toagroecological differences in sites of collection. Results obtainedencouraged in Argentina further collection missions for naturalizedpopulations of white clover.     

经营方式对蒙古栎次生林林下草本种群特征的影响

对不同经营方式下蒙古栎次生林林下草本种群特征进行了研究。结果表明:混交模式下草本植物种类要略多于纯林模式下;大多数草本在针阔混交模式下,高度、盖度、数量、频度等指标要大于纯林模式下,即混交模式更适于林下草本的生长繁衍及对资源的占有利用;混交林下草本在保持水分方面与纯林相比更具优势。     

Population differences in juvenile survival under increasing drought are mediated by seed size in cork oak (Quercus suber L.)

Many studies have focused on the physiological and morphological responses of Quercus suber to high temperatures and summer drought. Nevertheless, our understanding of the potential of this species to cope with climate change is incomplete. An increase in severity, length and frequency of summer droughts is expected in the Iberian Peninsula over the 21st century. We investigated the potential of cork oak to adapt to climate change in a 4-year study comparing seedling survival from thirteen Spanish populations in a common garden. Acorn size was evaluated as a possible adaptive trait enhancing stress resistance during establishment. Populations originating from sites with the driest summers exhibited the highest survival rates under dry conditions. These populations were characterized by bigger acorns, suggesting selection for this trait across sites experiencing drought. Our findings reveal that northern populations are not well adapted to cope with increasing drought but suggest that they might cope well with the moderate drought increase expected for these zones. However, continental populations are intermediately adapted to dry conditions, while drastic and fast increases in summer droughts are expected to occur in these regions. This extensive and quick change will provide scant chances to adapt making the populations of cork oak in these regions particularly vulnerable to the future climatic conditions.     

山西省翅果油树天然群体果实变异性的研究

以山西省平陆县三门镇、乡宁县西坡镇和崖下镇、翼城县甘泉镇4个代表性区域内的翅果油树为研究对象,对翅果油树的树高、地径、冠幅、果实和种子的长、宽、出仁率、出种率等经济性状测定并进行方差分析。结果表明,翅果油树果实的平均变异系数为12.5%,且变幅表现为果长(12.0%)果宽(10.8%),种长(12.1%)种宽(10.0%);崖下镇果实的果长、种长、种长/种宽明显高于其他3个分布区的;各分布区翅果油树的不同表型分化系数变化范围为0.00%~29.52%,群体间方差分量最大、最小的2个值分别是种长/种宽、果宽,群体内方差分量最大、最小的2个值分别是种宽、果长/果宽,变异来源于群体内单株间和单株内。     

不同稗草种群对五氟磺草胺的敏感性差异

为探讨不同地区稗草种群对五氟磺草胺的敏感水平,采用室内整株生测法测定五氟磺草胺对不同稗草种群的生物活性以及对不同稗草种群叶绿素含量、光合特性、叶绿素荧光参数和Rubisco活性的影响。结果表明,五氟磺草胺影响稗草Rubisco活性、最大光化学效率以及光合速率等生理指标,但不同稗草种群的变化略有差异。其中五氟磺草胺处理后4 d对安徽潜山稗草种群生理指标影响较大,五氟磺草胺3.75~60.00 g a.i./hm~2处理剂量下稗草Rubisco活性较相同种群空白对照显著降低24.45%~61.09%,15.00~60.00 g a.i./hm~2剂量下,稗草叶片净光合速率较对照显著降低30.04%~58.56%,60.00 g a.i./hm~2剂量下,稗草叶绿素含量和最大光化合效率分别较对照显著降低13.10~28.82%和6.64%~11.29%,而湖北武汉稗草种群叶绿素含量、叶绿素荧光参数以及Rubisco活性无显著变化,只是叶片净光合速率较相同种群空白对照显著降低18.82%~28.49%。整株生物活性测定结果表明,五氟磺草胺处理21 d后安徽潜山稗草地上部鲜质量ED90值最低,为14.936 g a.i./hm~2,而湖北武汉稗草的ED90值最高,为201.679 g a.i./hm~2,显著超过了五氟磺草胺生产使用的推荐剂量。可见湖北武汉稗草种群对五氟磺草胺敏感性明显低于其他地区稗草种群,生产中需要密切注意其抗药性水平的发展变化,及时调整化学防除策略。