不同种植密度对花生群体透光率的影响

以青花7号花生品种为材料,在田间地膜覆盖栽培条件下,系统研究了不同种植密度对花生群体透光率的影响。结果表明：随种植密度的增加,垄上行间和垄间上、中、下部的透光率均呈递减趋势。通过垄上行间和垄间中后期透光率的变幅大小分析,认为本试验种植密度以15万穴/hm2群体内光照分布较为合理。     

不同居群达乌里胡枝子茎解剖结构与其抗旱性的关系

于2007年9月运用光学显微镜对山西6个居群野生达乌里胡枝子(Lespedeza davurica)盛花期的茎解剖结构进行研究,并且运用方差分析、聚类分析、相关分析和隶属函数综合评价其抗旱性,为其抗旱能力的评价以及抗旱机理研究提供形态解剖学方面的依据。结果表明:15个指标中根据方差分析结果结合植物学知识选定11个指标,并聚成3类,分别反映了茎的维管组织特征、中柱结构和茎的宏观特性;通过相关分析选择表皮厚度、木质部厚度、茎直径、髓腔直径、导管直径和导管密度分别为各类的典型指标,应用隶属函数法综合评价其抗旱能力由强到弱依次为:阳泉>静乐>交口>太谷>沁水>沁源。     

秦巴山区油菜蚜虫优势种及有翅蚜消长规律研究初报

通过对油菜蚜虫优势种及其有翅蚜消长规律调查,结果表明:秦巴山区蚜虫为桃蚜和萝卜蚜混合发生,优势种为桃蚜,主要以无翅成若蚜在油菜等十字花科植物上越冬,其生活史属非全周期型。3月下旬为有翅蚜始见期,5月上旬为迁飞高峰期。做好4月上旬防蚜工作,是控制蚜虫传播病毒病的关键。     

四个不同基因型大豆品种生物学特征的研究

研究了4个不同基因型大豆(Glycine max)上海95-1、垦鉴14、早熟18、930257的生物学特征.结果表明,4个大豆品种的单株叶面积随时间的变化动态可以用修正的logistic曲线=k(1 ea bt ct2 dt3)-1来拟合.其单株最大叶面积与生育天数呈极显著正相关(r=0.9953, P<0.01),各品种单株叶面积日增长(cm2/株*日)最大值出现时间,上海95-1、恳鉴14与结荚始期相一致,早熟18和930257与开花期相一致,进入结荚期以后,叶面积日增长随时间日趋减缓.4个品种的地上部风干重增长动态可以用y=k(1 ea bt)-1方程(F>F0.01)来拟合.单株地上部风干重最大日增重值(g/株*日)与结荚盛期相一致,较单株叶面积最大日增速出现时间滞后15 d左右.上海95-1,垦鉴14,早熟18三品种地上部各器官干物质分配比例趋于一致,籽实重平均占36.3%,叶片重占25.1%,荚皮重占20.57%,茎重占17.93%;930257地上部生物量分配比例与上述三品种不相一致,其叶片所占比例最高,达35%,茎重占32.4%,粒重占18%,荚皮占14.8%.     

Evaluating ipê (Tabebuia, Bignoniaceae) logging in Amazonia: Sustainable management or catalyst for forest degradation?

Prized for their dense, rot-resistant wood, Tabebuia impetiginosa and T. serratifolia (vernacular name = ipê) are among the most valuable Amazonian timbers. We analyzed the geographical extent, spread and trajectory of ipê logging in Brazilian Amazonia, and evaluated harvest pressure on this forest resource. We also examine Tabebuia population response to reduced-impact logging, a more ecologically benign alternative to destructive conventional harvest practices in Amazonia. Based on eight years of population monitoring at multiple sites in the eastern Brazilian Amazon, we project second harvest ipê yields in forests logged using RIL under legally allowable (90% of commercial stems) and reduced (70%) harvest intensities.In recent years ipê harvests have declined or ceased in the majority of old logging frontiers in eastern Amazonia while spreading to new logging frontiers in central and southwestern Amazonia. With current timber market prices, transportation infrastructure and harvesting costs, logging of ipê would be profitable in an estimated 63% of the Brazilian Amazon; in the more remote logging frontiers only logging of ipê and a few other high-value timbers is currently profitable. All populations of T. impetiginosa and T. serratifolia in northeastern forests showed drastic population declines over multiple RIL harvests in simulations, with no indication of population recovery over the long term. We conclude from study of Tabebuia populations in eastern Amazonia and modeling of response to logging that these two species are endangered by logging activity and merit additional protection under forest legislation.     

Genetic and demographic responses of fragmented Acacia dealbata (Mimosaceae) populations in southeastern Australia

Genetic and demographic studies of fragmented populations of common plant species often reveal negative impacts that are likely to constrain persistence. Examining species that are broadly representative of functional groups within fragmented landscapes is one approach to providing a better understanding of how these processes will influence vegetation persistence. Acacias are a significant component of the Australian flora, with Acacia dealbata being a common and representative species of fragmented landscapes across New South Wales. Previous reproductive assessments of fragmented A. dealbata populations indicated significant constraints for small populations through low reproductive output mediated by fertilisation success. This study examined genetic diversity, mating system, and progeny growth parameters of the seed crops produced by these populations to assess whether further constraints to persistence could be detected. Spatially explicit simulation studies were also conducted to assess the persistence likelihood of fragmented populations. Landscape parameters such as population size and plant density were useful predictors for some of the genetic and demographic responses, but a poor response signal was generally observed. Strong evidence for a self-incompatibility mechanism was observed in A. dealbata and is likely to be the major driver of population persistence. Self-incompatibility in small populations limits mate availability and eliminates inbred progeny early in the reproductive cycle leading to poor reproductive output. The simulation data provides further evidence that mate limitation in smaller populations (<200 plants and 40 S alleles) constrains reproductive output and persistence. These data indicate that introducing new germplasm to smaller populations can dramatically improve their persistence likelihood.     

Matrix analysis to evaluate sustainability: The tropical tree Aquilaria crassna, a heavily poached source of agarwood

We used size-structured Lefkovitch projection matrix analysis to predict future trends in the survival of Aquilaria crassna (Thymelaeaceae), a tropical evergreen forest tree that has been highly sought after for its valuable aromatic wood (agarwood) for millennia. Data on growth, damage to trees by poachers, fruit production, seed dispersal and seedling recruitment were collected from a 30-ha plot in Khao Yai National Park, central Thailand that had seen moderate poaching. The population asymptotic growth rate, λ_a, and transient growth rate, λ_tr, found from using the matrix to project the observed population 48 years, were 1.002 and 1.005, respectively, with 95% confidence intervals of [0.985, 1.016] and [0.985, 1.023]. The stable size distribution obtained from the matrix was reasonably similar to the observed size distribution, suggesting that at the time of the study the population was not far from equilibrium. Sensitivity analysis and simulations of poaching on adult trees indicate that both λ’s are very sensitive to the removal of adult trees and the growth of preadult trees. In particular, the increase in tree mortality and decrease in preadult growth rate caused by agarwood collection seen in some areas could cause extirpation of the population. While in such cases the population appears to be poised on the brink of decline, several factors that we could not evaluate could alter its fate. First, adult deaths could stimulate recruitment of young under the parent trees; second, there is marked year-to-year variation in fruiting success and possibly recruitment; third, there is considerable spatial variation in tree density and recruitment, suggesting that attempts to evaluate future success need to encompass larger spatial and time scales.     

外源Bt基因导入对棉花叶片维管束汁液的生化物质含量及烟粉虱种群增殖的影响

以转Bt基因棉花"国抗22"和常规棉亲本"泗棉3号"为试材,研究外源Bt基因导入对棉花叶片维管束汁液中营养物质和次生物质含量以及烟粉虱种群增殖的影响.结果表明,和"泗棉3号"相比,"国抗22"叶片维管束汁液中可溶性糖含量较低;单宁浓度苗期较低,但花铃期两个品种无明显差异;花铃期游离氨基酸总量无明显差异,但谷氨酸、脯氨酸、丙氨酸含量均明显高于"泗棉3号";在苗期和花铃期两品种棉花叶片维管束汁液中均未检测到棉酚.取食苗期和花铃期"国抗22"棉花的B型烟粉虱内禀增长率rm分别比取食"泗棉3号"对应生育期的高13.7%和20.2%.研究表明,外源Bt基因的导入影响转基因棉花中可溶性糖、游离氨基酸和其他抗生物质的合成,从而影响烟粉虱的种群发展.     

The size and status of the population of southern sea lions Otaria flavescens in the Falkland Islands

Pup production of southern sea lions in the Falkland Islands was estimated to be 80,550 (total population ca. 380,000) in 1937, but by 1965 it had fallen to around 6000; a 93% reduction in under 30 years. We describe the results of an aerial survey of part of the breeding population in 1990 and comprehensive ground counts of the entire population in 1995 and 2003. Results indicate that the decline continued. In 1995, 63 breeding and 42 non-breeding groups were found. Pup production was estimated at 2034 pups; less than 2.7% of the 1930s estimate. All known and potential sites were revisited in 2003. 2747 pups were counted at 68 breeding sites, seven of which were new since 1995. Results indicate that between 1965 and 1990 the population reached a minimum of less than 1.5% of the 1937 population. Since then, pup production has increased at a rate of 8.5% p.a. between 1990 and 1995 and at 3.8% p.a. between 1995 and 2003.The Falklands' trajectory is similar to that of the adjacent Argentinian population. The causes of these declines are not clear. Around 44,000 sea lions were killed in the Falklands between 1935 and 1962, more than 500,000 were taken in Argentina in the same period. We present the results of a simple population model which suggests that, if sea lions migrated between the two areas, the combined hunt may explain the initial decline in the Falklands population. However, the continued decline after 1965 is as yet unexplained.     

不同轮回选择方法对玉米窄基群体的改良效果

利用轮回选择进行群体改良,是玉米种质扩增与改良的有效方法,能为选育优良自交系提供基本素材,进而提高选育自交系及杂交种的效率。本研究以玉米窄基群体P4C0及其经过不同轮回选择方法改良的10个群体为材料,通过多点田间表型鉴定和配合力测定,研究不同轮回选择方法对玉米窄基群体的改良效果,利用SSR分子标记分析不同轮回选择方法对群体遗传多样性的影响。结果表明,几种轮回选择方法都能有效改良群体的主要性状及其一般配合力(GCA)。以时间计算,控制双亲混合选择(MS)对群体P4C0主要性状及其GCA改良效果优于半同胞-S2:3(HS-S2:3)轮回选择,但在株高和穗位高的改良上,HS-S2:3选择效果较好。以轮次计算,开放改良对群体P4HSC1主要性状及其GCA的改良效果优于MS,但开放改良后,群体株高和穗位高有较大幅度的增加。不同轮回选择方法对群体遗传多样性和遗传结构的影响不尽一致。P4C0经过5轮MS后,在群体改良的低代,群体遗传多样性得到了较好的保持,而多代的改良导致群体遗传多样性下降;P4C0经过1轮HS-S2:3选择后,遗传多样性比P4C0有较大幅度的下降。P4HSC1经过1轮开放改良后,遗传多样性有较大幅度的增加。P4HSC1经过3轮MS改良后,群体遗传多样性呈增大的趋势,但每轮增加的幅度均较小。