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41.
S. E. Shumway T. L. Cucci M. P. Lesser N. Bourne B. Bunting 《Aquaculture International》1997,5(1):89-99
Juvenile scallops (<2 mm shell height) of three species (Placopecten magellanicus, Patinopecten yessoensis, Argopecten irradians) were fed mixed, unialgal cultures. Scallops were fed a total of six algal clones simultaneously and clearance rates were
monitored using flow cytometric techniques. In another experiment, scallops were presented with natural assemblages of particulate
matter as a food source. Data are presented on differences in clearance rates for the individual algal species as well as
size-related differences of algal clones, and uptake of chlorophyll vs. non-chlorophyll cells, both within and between scallop
species. Significant differences in clearance rates of individual algal species have been found within and between scallop
species. Particle selection does not appear to be based upon size alone and is apparently based on other characteristics of
the algae as well. The results demonstrate pre-ingestive sorting. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(4):511-527
Profiles of semi-arid-zone soils in Punjab, northwestern India, were investigated for different forms of copper (Cu), including total Cu, diethylenetriaminepentaacetic acid (DTPA)–extractable Cu, soil solution plus exchangeable Cu, Cu adsorbed onto inorganic sites, Cu bound by organic sites, and Cu adsorbed onto oxide surfaces. When all soils were considered, total Cu content ranged from 7 to 37 mg kg?1, while DTPA-extractable and soil solution plus exchangeable Cu contents ranged from 0.30 to 3.26 mg kg?1 and from 0.02 to 0.43 mg kg?1, respectively. Copper adsorbed onto inorganic sites ranged from 0.62 to 2.6 mg kg?1 and that onto oxide surfaces ranged from 2.0 to 13.2 mg kg?1. The Cu bound by organic sites ranged from 1.2 to 12.2 mg kg?1. The magnitudes of different forms of Cu in soils did not exhibit any consistent pattern of distribution. Organic matter and size fractions (clay and silt) had a strong influence on the distribution of different forms of Cu. The content of all forms of Cu was generally greater in the fine-textured Alfisols and Inceptisols than coarse-textured Entisols. Soil solution plus exchangeable Cu, Cu held onto organic sites, and and Cu adsorbed onto inorganic sites (crystalline) had significant positive correlations with organic carbon and silt contents.The DTPA Cu was positively correlated with organic carbon, silt, and clay contents. Total Cu content strongly correlated with silt and clay contents of soils. Among the forms, Cu held on the organic site, water soluble + exchangeable Cu, and Cu adsorbed onto oxide surface were positively correlated with DTPA-extractable Cu. The DTPA-extractable Cu and soil solution plus exchangeable Cu seems to be good indices of Cu availability in soils and can be used for correction of Cu deficiency in the soils of the region. The uptake of Cu was greater in fine-textured Inceptisols and Alfisols than coarse-textured Entisols. Among the different forms only DTPA-extractable Cu was positively correlated with total uptake of Cu. 相似文献
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[目的]初选一批落羽杉优良家系。[方法]对江汉平原三台林场6年生落羽杉15个家系子代测定林的胸径、树高和材积进行调查和分析。[结果]不同家系间的胸径、树高和材积差异极显著,胸径、树高和材积性状家系遗传力均在59%以上,各性状受到中等至较强度的遗传控制,其中胸径家系遗传力高达79.82%;利用育种值评分法从15个参试家系中初步选出了6个优良家系,平均遗传增益分别为6.9%、4.6%和11.3%,平均现实增益分别为8.7%、6.9%和16.3%,其中③号家系胸径、树高和材积均有最高的遗传增益和现实增益。[结论]所选出的优良家系生长优势明显,可作为优良遗传材料进行保存,同时也可为落羽杉优良家系的长期选择奠定基础。 相似文献
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渭北黄土塬区地埂花椒林的水保作用与生态经济效益调查研究王忠林,薛智德(西北林学院,陕西杨陵712100)渭北黄土塬区现有梯田和台田面积8.44万hm2,农田地埂占梯田和台田面积的0.5%~1%。地埂上营造花椒林,既充分利用了这部分空地,解决了林粮争地... 相似文献
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Genetic shifts are predicted to be greatest when highly diversematerial originating from an arid environment is bulk multiplied inirrigated and fertilised conditions. This is a key problem if largequantities of quality native seed are needed for restorationpurposes. In Presaharian Tunisia, we investigated two intermingledyield aspects of irrigated seed multiplication of Stipalagascae R. and Sch.: (1) nitrogen fertilisationand (2) selection for vegetative vigour. We set up twocontiguous nitrogen fertilisation trials, one withnon-selected seeds (from a nearby locality), and onewith selected seeds (48 clonal lines seeded in replicatedrows), and compared straw yields. Both selected and unselectedmaterial did not respond to more than 50 kg of nitrogenper ha. Unfertilised yields of both trials were similar,but the straw yield of fertilised selected material was more than100% higher than the straw yield of fertilised unselectedmaterial. In the trial with selected material, we collected straw andleaf yields per row, and scored each row for vigour and for phenologyduring three successive growing seasons. Genotypic differences inseed output and in mortality were large and mainly driven byvariation in potential straw for leaf ratios.The compromise between high yields and high genetic variation couldconsist of the following principles. (1) Create driergrowing conditions so that the actual straw forleaf ratio stays below the genotypic potential. (2) Useinstead fertilisation and selection to enhance seed yields.(3) Avoid bulk multiplication. 相似文献
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氰戊菊酯、马拉硫磷及其混剂汰选选育棉铃虫抗药性研究 总被引:4,自引:0,他引:4
用氰戊菊酯、马拉硫磷及菊马混剂分别汰选棉铃(Heliothis armigera)种群16代,每三代测定1次各种群对相应汰选药剂的敏感水平。结果表明,以上三个汰选种群对相应药剂的抗药性分别增长了68.02、7.76和3.48倍,氰戊菊酯单剂比菊马混剂抗性增长快19.6倍,混剂显示出对棉铃虫抗性显著的延缓作用。用计算机模拟预测混剂使用寿命,若3种药剂均连续使用30次则氰戊菊酯、马拉硫磷、菊马混剂的抗药性将分别提高817.5、14.2和5.2倍;若以抗性上升30倍及每年用药2-3次为标准,菊马混剂比单用氰戊菊酯可延长5倍的使用寿命。笔者认为把增效混剂作为一项措施组装到抗性治理方案(IRM)中去,科学合理地治理棉铃虫的抗药性是一个行之有效的措施。 相似文献