蓝标型显性核不育小麦的特性及其F1杂种优势分析

为了使小麦显性太谷核不育基因Ms2在杂种小麦上得以利用,以创制的显性蓝粒附加系97-866为基础,转育成功8份不同基因背景的新不育系,并对这8个不育系的粒色和育性分离状况以及杂种优势进行了分析.结果表明,在这8个新不育系的后代中,蓝粒不育株占20.6%～23.8%,平均为22.3%;白粒非矮秆可育株占77.6%,其它类型仅占0.1%,表明蓝粒基因、Ms2和Rht10基因均位于附加染色体上,而且连锁紧密.但对性状不同轮回亲本,矮败蓝粒于的传递率有差异,部分轮回亲本间差异达到5%显著水平,同一轮回亲本在不同年份间对蓝粒不育株传递率的影响差异不显著.F1代杂种优势表现为既有超亲优势又有超标优势,筛选出3个杂交种的籽粒产量超过对照15%以上.     

小麦品质性状杂种优势及其配合力研究

采用二组品质性状不同的12个亲本材料,通过6×6NCⅡ完全双列杂交设计,配制了36个组合,对小麦品质性状的杂种优势及其配合力进行了研究。结果表明,除谷蛋白大聚合体的平均杂种优势较大外,其它品质性状后代的平均杂种优势较小,但组合间杂种优势具有显著差异;大多数品质性状都受基因加性效应和非加性效应影响,以加性效应为主。在亲本之间、性状之间以及组合之间一般配合力效应值和特殊配合力效应值的差异均较大。除干面筋含量以外,各品质性状的亲本间和组合间方差分别达到显著或极显著差异水平。     

大豆有效营养面积研究

提出作物有效营养面积新概念,并用回归理论对此进行试验研究。通过试验,建立大豆植株个体营养面积与产量关系的模型,优化解析出大豆单株有效营养面积为2209.9cm2,即有效株行距为47.0cm。大豆最佳营养面积为546.9cm2,即最佳株行距为23.4cm。据此阐明目前生产上广泛采用67～70cm的垄作,已超过大豆的有效株行距,造成了土壤资源等的浪费。垄作区采用45～50cm的垄距,平作区采用23×23cm的株行距种植,将会更有利于大豆群体产量的提高。     

6个玉米人工合成群体的配合力分析

采用不完全双列杂交遗传交配设计,对6个玉米人工合成群体的配合力进行了研究。结果表明,多数农艺、经济性状的GCA群体间存在显著或极显著差异,少数经济性状的SCA在群体和测验种的组合间存在显著或极显著差异,群体P4、P2和P7主要经济性状GCA较高,优于对照高产组合出现次数较多,且群体P2和P7株高GCA表现较好,育种潜力较大。     

不同环境条件下玉米子粒淀粉含量的配合力效应及杂种优势分析

以选自不同杂优类群、淀粉含量不同的10个自交系为亲本,按照Griffing设计配成正反交90个组合,在河南3个地点随机区组试验。测定子粒淀粉含量,分析了基因型、地点及其互作对玉米子粒淀粉含量的影响,进行了配合力方差和杂种优势分析。结果表明:①地点与基因型之间差异均达极显著水平,地点×基因型的互作效应差异不显著。②亲本淀粉含量的一般配合力(GCA)和特殊配合力(SCA)效应差异均达极显著水平,组合的淀粉含量以GCA效应为主;自交系郑58的淀粉含量和GCA效应均较高,是高淀粉育种的重要资源之一。③所用组合的淀粉含量均表现正向优势,平均中亲优势率4.24%,超高亲优势率1.64%。不同组合优势大小不一,变幅分别为0.31%～9.05%和-1.80%～6.24%;选自不同杂优类群的高淀粉自交系易配出高淀粉组合,亲本之一含量不宜过低。④母体效应对F2当代子粒淀粉含量无明显影响。     

Scale-dependent homogenization: Changes in breeding bird diversity in the Netherlands over a 25-year period

Changes in breeding bird diversity in the Netherlands between 1973-1977 and 1998-2000 were evaluated by testing three hypotheses related to the loss of biodiversity: (1) species diversity is declining, (2) biotic homogenization is increasing and (3) rare species are declining more severely than abundant species. Using data collected for two successive national breeding bird atlases, changes in diversity were assessed at different spatial scales (local, regional and national) and among species characteristic for different landscapes (farmland, woodland, heathland, wetland, coastal habitats and urban habitats). National species richness, diversity and equitability had increased between the two atlas periods, with more species increasing than decreasing in range and abundance. Most species in the large groups of woodland and wetland birds showed positive trends, whereas most in the smaller groups of heathland, reed-breeding and meadow birds showed negative trends. However, findings varied between regions and localities. Increases in species richness occurred mainly in regions in the low-lying, western part of the country which were previously relatively poor in species. By contrast, species richness decreased in some previously species-rich regions in the eastern part of the country. This has resulted in a homogenization of breeding bird communities between regions. We advocate the conservation and restoration of regional identity as a priority for landscape planning in the Netherlands. We did not find a clear relation between species abundance and trends, although both rare and very abundant species tended to decrease on average.     

Within-site habitat configuration in reserve design: A case study with a peatland bird

This study assesses the effects of considering within-site habitat configuration when designing reserve networks. This attribute takes all its importance in situations where the long-term integrity of (within-site) habitat patches cannot be preserved without protecting their surrounding environment. We addressed this issue through the concrete problem of selecting a reserve network of natural peatlands in southern Québec, Canada. We used a reserve-selection algorithm that minimized the total number of peatlands to include within networks. The algorithm was constrained to include peatlands containing habitat patches that met specific size thresholds. Five habitat-clustering thresholds were used to set the eligibility of each site to the selection process. The resulting reserve networks were evaluated according to their representation efficiency and to the expected consequences for the Palm Warbler (Dendroica palmarum), an area and isolation-sensitive bird restricted to peatlands in southern Québec.Constraining the algorithm to include peatlands showing increasingly larger patches of habitats led to larger networks, both in terms of area and number of sites, and to networks composed of smaller sites. These effects increased with the representation target (i.e., the % of each habitat preserved). With respect to the Palm Warbler, selecting peatlands with larger patches of habitats had only an indirect effect on its site-occupancy pattern. Indeed, despite the fact that the probability of occurrence of the warbler was negatively correlated with the size of habitat patches, the habitat-clustering threshold influenced the incidence of the warbler mainly via its effect on the physical attributes of the selected networks - including the area, isolation level, and the number of selected sites. Because increasing the habitat-clustering threshold led indirectly to a greater regional availability of prime breeding habitats for the Palm Warbler, it mitigated the severe negative impact of an hypothetical alteration or destruction of non-selected peatlands. Our study thus emphasizes the importance of determining how the different factors describing within-site configuration are correlated with other intrinsic characteristics of the sites available to the selection process before opting for a site-selection strategy.     

斜纹夜蛾自然种群数量动态预测研究

根据斜纹夜蛾发育历期与温度的数学关系、卵和幼虫田间自然存活率及田间逐日产卵量参数,研究建立了斜纹夜蛾种群数量动态预测的变维矩阵模型。并运用该模型预测南昌市郊区甘蓝田斜纹夜蛾自然种群数量动态,其预测结果与实际观测结果基本相符。     

Seed banks in plant conservation: Case study of Santa Cruz tarplant restoration

Although conservation and restoration practitioners have focused on maximizing aboveground population size and seed set of rare plants, a clear understanding of seed bank dynamics is crucial to managing these species. Santa Cruz tarplant (Holocarpha macradenia) is a threatened annual forb restricted to coastal prairie habitats in central California. Holocarpha produces disk achenes germinating within a year of production and ray achenes forming a persistent seed bank. We constructed both deterministic and stochastic demographic models for a restored Holocarpha population, using demographic rates measured separately for unmanipulated plants and plants growing in plots where vegetation was clipped. The deterministic models indicated that regardless of germination from the seed bank, the population would decline without clipping or similar treatments that enhance survival and reproductive output. Deterministic models showed only a slight positive effect of increased ray seed germination rates on population growth, which would need to be balanced against a potential loss of buffering against environmental variation as the dormant seed bank was reduced. Our stochastic simulations suggested that extinction risk for Holocarpha populations would be minimized by intermediate levels of ray seed germination. Thus, managers should focus on improving the performance of aboveground plants before considering actions to stimulate germination, since the former will yield a greater increase in deterministic population growth and not sacrifice any buffering effect of the seed bank. This case study emphasizes the importance of considering dormant seeds and seed banks in designing successful restoration and management strategies for plant species at risk of extinction.     

Potential causes of population declines in forest fragments in an Amazonian frog

Forest fragmentation results in population declines and extinctions for many forest vertebrates, but little is known about the mechanisms causing declines in fragments. We investigated potential causes of declines in forest fragments for an Amazonian forest frog (Colostethus stepheni) at an experimental fragmentation study site in central Amazonian Brazil using field estimates of abundance and vital rates coupled with population simulations. Although adult male survival was not reduced by fragmentation, mean clutch size was reduced by 17%. Population simulations demonstrate that a reduction in clutch size of this magnitude is sufficient to cause the observed magnitude of population declines in fragments. Female snout-vent length was also reduced in fragments and may be related to the observed reduction in clutch size.