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31.
大豆性状整齐度与产量的关系   总被引:2,自引:0,他引:2  
观察测定了同一品种在同一条件下大豆性状的整齐度,同一品种在不同条件下性状的整齐度,不同品种在同一条件下性状的整齐度,统计分析了性状整齐度与实收产量之间的关系,结果表明,要获得大豆高产稳产,应注意植株间荚数和粒数的整齐度。  相似文献   
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采用样线与样方相结合的调查方法,根据点相关系数及X^2值连续性较正公式,测定了小兴安岭凉水自然保护区具有环境梯度的7个森林类型内主要蕨类植物的种间联结。结果表明:各林型均有其适生的蕨类类群,与该类群呈正联结的蕨类种其数量分布也多,反之刚少;具有环境梯度的不同林型序列,反映出蕨类植物适生生境的不同,据此,将本区主要蕨类植物分为4种生态类型。  相似文献   
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1982—1984年在温室和田间对3个慢叶锈品种:中引305、中引515、中引709,2个快叶锈品种:无沙八号、纳罗的研究表明,小麦慢叶锈抗病品种具有8个抗病特性:(1)田间发病迟、普遍率增长缓慢,严重率低且发展速度慢;(2)潜伏期较长;(3)侵染频率较低;(4)夏孢子堆较小;(5)菌丝和夏孢子堆面积扩展速度慢;(6)产孢能力较弱;(7)对叶锈菌生理小种特异性不明显;(8)对产量影响不显著。慢叶锈抗病性随植株生长而增强,应用病害发展曲线下面积(AUDPC)的A值比侵染速率r值和冈珀茨方程的k值能更好地表达小麦品种的慢叶锈抗病性。利用温室测定苗期潜伏期、侵染频率和田间发病盛期旗叶的严重率指数可以作为小麦慢叶锈抗病品种的选育指标。  相似文献   
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1. Light‐weight (Babcock B300) and medium‐weight (Warren‐SSL) hens were offered diets, containing 0, 100 or 200 g dried poultry manure (DPM) and 11.49, 11.12 or 10.83 MJ metabolisable energy/kg respectively, between 18 and 70 weeks of age. The true protein, metabolisable energy, calcium and phosphorus contents of the DPM, from caged layer hens, were used in the diet formulation.

2. The hen‐housed laying performance of hens offered the DPM‐containing diets was significantly better for number of eggs laid and total egg mass produced but the performance of the control groups was lower than would normally be expected of those stocks. The reason for the lower rate of lay and higher mortality of hens fed on the control diet was not identified. The amount of food consumed increased as the energy content of the diet decreased and the efficiency of food conversion (EFC) of the lightweight strain was reduced; there was no significant effect on the EFC of the medium‐weight hens.

3. The inclusion of DPM in the diets had no effect on albumen quality or on the incidence of hair‐cracked, cracked or broken eggs. However, with both strains of hens, shell weight and shell thickness were poorer when 100 or 200 g DPM/kg diets were fed.  相似文献   

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Engineering resistance against various diseases and pests is hampered by the lack of suitable genes. To overcome this problem we started a research program aimed at obtaining resistance by transfecting plants with genes encoding monoclonal antibodies against pathogen specific proteins. The idea is that monoclonal antibodies will inhibit the biological activity of molecules that are essential for the pathogenesis. Potato cyst nematodes are chosen as a model and it is thought that monoclonal antibodies are able to block the function of the saliva proteins of this parasite. These proteins are, among others, responsible for the induction of multinucleate transfer cells upon which the nematode feeds. It is well documented that the ability of antibodies to bind molecules is sufficient to inactivate the function of an antigen and in view of the potential of animals to synthesize antibodies to almost any molecular structure, this strategy should be feasible for a wide range of diseases and pests.Antibodies have several desirable features with regard to protein engineering. The antibody (IgG) is a Y-shaped molecule, in which the domains forming the tips of the arms bind to antigen and those forming the stem are responsible for triggering effector functions (Fc fragments) that eliminate the antigen from the animal. Domains carrying the antigen-binding loops (Fv and Fab fragments) can be used separately from the Fc fragments without loss of affinity. The antigen-binding domains can also be endowed with new properties by fusing them to toxins or enzymes. Antibody engineering is also facilitated by the Polymerase Chain Reaction (PCR). A systematic comparison of the nucleotide sequence of more than 100 antibodies revealed that not only the 3′-ends, but also the 5′-ends of the antibody genes are relatively conserved. We were able to design a small set of primers with restriction sites for forced cloning, which allowed the amplification of genes encoding antibodies specific for the saliva proteins ofGlobodera rostochiensis. Complete heavy and light chain genes as well as single chain Fv fragments (scFv), in which the variable parts of the light (VL) and heavy chain (VH) are linked by a peptide, will be transferred to potato plants. A major challenge will be to establish a correct expression of the antibody genes with regard to three dimensional folding, assembly and intracellular location.  相似文献   
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