稻瘟病菌致病性变异及稳定菌系的筛选

本文利用中国稻瘟病菌生理小种鉴别品种及日本的具已知基因鉴别品种,研究了日本的稻瘟病菌鉴别菌系,我国北方稻区辅助鉴别菌株及保存5～10年菌株的致病性。研究结果表明,菌株的致病性受其自身致病基因及环境因素等多方面影响,在众多的菌株中仍有稳定菌株存在。讨论了稻瘟病菌致病性变异性。提出了稻瘟病菌稳定菌株的筛选方法。     

安徽省茄子地方种质资源研究Ⅰ植株性状、熟性性状与果实性状的变异和相关分析

以安徽省的13个茄子地方种质为试材,对12个植物性状的变异和性状间的相关进行了分析。结果表明（1）各性状变异系数由大到小依次为单株早期果数＞果形指数＞果实纵径＞单株总果数＞单果重＞果实横径＞开展度＞株高＞茎粗＞始花节位＞现蕾日数＞开花日数。（2）株高与始花节位、现蕾日数、开花日数分别是极显著成显著正相关,与单株早期果数、单株总果数、果形指数呈显著负相关。（3）单株早期果数和单株总果数分别与果实纵径、果形指数呈显著正相关。单果重与果实横径呈极显著正相关,与果形指数呈显著负相关。果实横径与果实纵径是极显著负相关。     

中国荷斯坦牛乳中体细胞数变化规律的研究

采用最小二乘法分析了来自三个牛场自2002年1月~2004年3月1 973头荷斯坦牛的13 841条DHI测定日SCC记录。分析表明SCC的平均数为64.99×1 000个/mL,标准差为110.19×1 000个/mL,不同的场、不同的季节对SCC的影响极显著(P<0.01),不同的年对SCC的影响不显著(P>0.05),不同胎次、不同泌乳月对SCC影响极显著(P<0.01)。SCC随着胎次和泌乳月的增加有升高的趋势。     

A model for estimating how variability of biological parameters affects economic factors in an integrated turkey farm

Turkeys, as well as other poultry meat, are marketed as a healthier alternative to red meat. At the same time, the necessary investment in integrated turkey projects is 65% higher than for similar broiler projects. This explains the importance of rigorous evaluation of new turkey farms, including their sensitivity to biological parameters. We present a method of evaluating poultry projects that takes simultaneous variability of several biological parameters into account, using a bio-economic model, stochastic simulation, and an integrated turkey farm in Russia as a real-life example. The algorithm based on the Cholesky decomposition of the covariance matrix was used to generate a multivariate normal random vector of biological parameters. The bio-economic model takes into account simultaneous variability of major input biological parameters related to all stages of an integrated poultry farm: survival, hatchability, ratio of carcass weight to live weight, and number of eggs per layer. The highest variability of the output economic indices was estimated for internal rate of return: the coefficient of variation (CV) of this major economic index was approximately 240% of the CV of the input biological parameters. Such estimation can be used to analyze a project's economic risks, i.e., variability in production cost and profitability.     

土壤重金属污染健康风险评估新视角 ——概率风险评估的源起及展望

评估土壤重金属污染对人体产生的危害,是土壤环境风险管理的重要前提.概率风险评估秉持表征不确定性和变异性的理念,为土壤重金属污染健康风险评估带来全新视角.为强化对概率风险评估的理论认知,推动其在土壤重金属暴露风险评估领域的深入应用,本文结合文献计量及整合分析方法,系统阐述了概率风险评估的理论基础及内涵演进,进一步将其与传...     

旱塬冬小麦氮磷肥效及其利用率的变异性研

多年试验研究结果表明,氮(N)磷(P)肥对旱塬冬小麦有显著增产效果,但其随小麦品种、年度波动性很大。N、P肥利用率年际间变化很大,且随其用量的增加而降低。1984～1995年(供试品种"长武-131")N肥利用率变幅为6.4％～58.6％,变异系数为48.7％;P肥利用率变幅为3.7％～19.8％,变异系数为39.5％。1996～1998年(供试品种"长武-134")肥料用量由45kg／hm2增至180kg／hm2,N肥利用率由42.9％降至25.4％(平均36.3％),P肥利用率由10.8％降至3.2％(平均7.2％)。肥料利用率与施肥利润高低并不同步,以肥料利用率作旱塬地区肥料生产效益的度量存在很大局限性,通过分析N与P的连应效应表明,N、P配施是提高其相互利用率的有效途径。     

Collection and Characterisation of Malabar Tamarind [Garcinia cambogia (Gaertn.) Desr.]

A collaborative crop specific exploration and collection mission to collect the germplasm and to study the population size of male and female/hermaphrodite trees of Malabar tamarind [Garcinia cambogia (Gaertn.) Desr.] in the area of its diversity was undertaken during July 2002 in Kerala and Karnataka. A total of 56 accessions of Malabar tamarind were collected. Two collections of Malabar tamarind were found to be very specific because of the uncommon fruit colour, which is pinkish red. All the collected accessions are grown at National Bureau of Plant Genetic Resources (NBPGR) Regional Station, Thrissur for characterisation and conservation. Extensive range of variability was found in fruit colour, shape, size and nature of branching and canopy of trees. Characterisation of 13 fruit and five seed characters was done for 51 accessions. The variability was found to be maximum for nipple length (74.8%) and minimum for fruit girth (12.8%). Two promising accessions were identified based on mean fruit weight (161 g) in IC 354028 and mean rind thickness (15 mm) and mean rind weight (125 g) in IC 354019.     

Variability of cotton (Gossypium hirsutum L.) with regard to earliness

Eighty cotton varieties (Gossypium hirsutum L.) from the collection of VIR (N.I. Vavilov Research Institute of Plant Industry, St. Peterburg, Russia) collection were studied for variability with regard to the duration of their vegetation period. The experiments were carried out in the conditions of the marginal zone of the cotton growing area, that is the city of Krasnodar in the Russian Federation. Thirty-four varieties were studied in 1996–1998, forty-six varieties in 1997–1998. The purpose of this research was to determine the threshold of sensitivity in the varieties of the duration of the period of vegetative growth, which depends upon weather conditions, and to record variations in morphological characters associated with earliness. The data obtained were processed by the method of statusmetry. The mathematical models which were constructed showed the relationship between the criteria for earliness and other morphological and agronomic characters of the plants.     

大豆蛋白质及脂肪含量的遗传和选择效果研究：Ⅲ.早期世代的变异与遗传进度

大豆的蛋白质及脂肪含量都是典型数量性状,F_2呈常态分布,F_2与MP几乎相等;F_2变幅受双亲限制,很少出现超亲个体;裂区方差分析进一步表明在F_2和F_3代正反交均无显著差异。五性状相关值表明产量与脂肪含量的负作用较大,完全粒率与蛋白质含量的负作用较大。蛋白质与脂肪含量的遗传力和遗传进度估值较高,表明早世代在组合间和系统间进行选择即可奏效。     

Daily Variability of Strongyle Fecal Egg Counts in Horses

Strongyle parasites are ubiquitous in grazing horses and constitute a potential threat to equine health. Feces were collected from six horses four times daily over a period of 5 days. Fecal egg counts (FECs) were performed to identify any diurnal rhythms in strongyle egg shedding and to quantify variability at the different levels: individual horses, repeated counts, repeated subsamples, different time points, and different days. No significant differences in FECs were found between the different time points (P = .11). The variables—horse, day, subsample, and egg count—accounted for a variance of 104.83, 0.10, 7.24, and 5.61, respectively. The apparent lack of additional variability between the four different time points suggests that time of the day chosen for collecting fecal samples does not constitute a source of error in field studies. The majority of variability exists between different subsamples and repeated egg counts on the same subsamples, whereas the variability of FECs between following days can be considered negligible. The findings of this study have implication for designing and performing field surveillance of strongyle FEC levels and applying the FEC reduction test for evaluating anthelmintic efficacy.