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61.
西瓜嫁接育苗与机械嫁接技术研究进展 总被引:1,自引:0,他引:1
西瓜是我国园艺生产中的重要经济作物,为了克服连作而引起的枯萎病、根结线虫病和土壤盐渍化等问题,嫁接技术被广泛的应用于西瓜生产。人工嫁接劳动强度大,嫁接和管理用工量大、技术要求高,是嫁接西瓜苗推广应用的主要限制因素。在回顾西瓜嫁接育苗技术发展的基础上,阐述了机械嫁接机及其配套的断根嫁接、大接穗嫁接、苗床四段式管理等关键技术在西瓜工厂化育苗中的应用。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):409-414
Second-year Norway spruce seedlings [Picea abies (L.) Karst.] grown in containers were divided into three fertilization levels in August [5, 15 and 25 mg nitrogen (N) seedling?1]. The resulting foliar concentrations of N were 11.0, 13.1 and 15.8 g kg?1, respectively. Seedling height (mean 26.0 cm) did not differ among treatments. The next spring, the seedlings were tested in two experiments. (1) The seedlings were transplanted into pots containing sandy soil in the greenhouse, where they were fertilized with either pure water or nutrient solution (22 mg N l?1). (2) The outplanting performance of the autumn-fertilized seedlings was tested on a sandy field. In the greenhouse experiment, the autumn fertilization level affected height growth and root egress of the seedlings significantly, but less than fertilization with a nutrient solution after planting. In the field experiment, during the first season after transplanting shoot growth of the seedlings increased with the level of autumn fertilization. After the second and third seasons, the seedling stem volume was highest with the highest level of autumn fertilization. These results suggest that, by improving the preplanting nutrient status of seedlings, the growth of shoot, stem diameter and root biomass can be enhanced after planting, especially on nutrient-poor soils. However, heavier autumn fertilization than that used here may yield a greater and more persistent increment in growth. 相似文献
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通过"从主链接枝"原子转移自由基聚合(ATRP)法,采用分步聚合策略,成功制备了一种乙基纤维素接枝嵌段共聚物乙基纤维素-g-甲基丙烯酸月桂酯-b-甲基丙烯酸四氢糠基酯(EC-g-P(LMA-b-THFMA))。对聚合物的热力学性能研究发现:共聚物中存在两个热转变,分别发生在-35℃和49~56℃时,表明该共聚物存在微相分离;机械性能分析表明该共聚物具有优异的热塑性弹性体行为,伸长率为89%~147%,拉伸强度为1.7~9.5 MPa。循环拉伸机械性能研究表明EC-g-P(LMA-b-THFMA200)的弹性恢复系数高达92%以上。乙基纤维素接枝共聚物的机械性能具有明显的增强作用,较线性聚合物P(LMA-b-THFMA)的机械强度提高了1.36倍。 相似文献
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Annette Kolb 《Biological conservation》2008,141(10):2540-2549
In fragmented landscapes plant species are often confined to remnants of formerly more widespread habitats, with many of their populations being small and isolated. This study experimentally examined the effects of population size and isolation on pollination, herbivory and reproductive success in the forest herb Phyteuma spicatum (Campanulaceae). In an experiment in which population size and isolation were manipulated using plants from the same origin, population size positively affected pollinator visitation, but did not alter the generally high levels of herbivory. As a result, seed production was higher in large populations. Conversely, plants originating from 14 natural populations of varying size and degree of isolation did not differ in reproductive success when grown in the same environment, suggesting similar attractiveness to pollinators and reproductive potential. The intensity of herbivory, however, was higher in progeny of small populations, at least in terms of the proportion of biomass removed. In both experiments, there were no effects of population isolation. The results suggest (1) that small population size decreases reproductive success via direct negative effects on plant-pollinator interactions, (2) that this pattern is not offset by herbivory, but (3) that herbivory enforces fragmentation effects on pollination by further reducing the number of flowering individuals and (4) that habitat fragmentation may influence plant fitness by affecting plant response to herbivory. The effects of habitat fragmentation on plant populations in present-day landscapes are thus complex, illustrating the need for more integrated studies in conservation biology that take into account both mutualistic and antagonistic plant-animal interactions. 相似文献
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Per M. Jepsen Christina V. Thoisen Thibaut Carron‐Cabaret Aleix Pinyol‐Gallemí Sren L. Nielsen Benni W. Hansen 《Journal of the World Aquaculture Society》2019,50(1):104-118
Marine aquaculture facilities positioned far from the sea need access to seawater (SW); hence, commercial salts are often the chosen solution. In marine hatcheries, most fish larvae require live feed (zooplankton) that are in turn fed with microalgae. The objective of this research was to investigate the applicability of commercial salts and clarify the potential effects on the cultivation of the microalga Rhodomonas salina and the copepod Acartia tonsa. Three commercial salts were tested, Red Sea Salt (RS), Red Sea – Coral Pro Salt (CP), and Blue Treasure Salt. R. salina was cultured at salinities of 10, 20, and 30 psu resulting in equal growth rates at salinities 20 and 30 in SW and RS mixed with deionized (DI) water. The optimum salinity for R. salina was 29 psu. For A. tonsa eggs, we observed highest hatching success in 30 psu with CP or RS mixed with DI water. The egg hatching success was not affected by salinities 15–40 and optimal hatching was obtained at 27 psu. Results confirm it was possible to use commercial salts for rearing of both R. salina and A. tonsa, widening the application of these species for aquaculture facilities without access to SW. 相似文献
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AIM: To reduce thrombus formation after coronary artery bypass graft,we investigated the antithrombotic effect of human tissue factor pathway inhibitor (TFPI) gene delivery on vein grafts. METHODS: The eukaryotic expressed plasmid vector pCMV-(Kozak)TFPI was constructed. Through pressurizing infusion,vein endotheliocytes were transfected with cationic liposome containing the plasmid vector pCMV-(Kozak)TFPI. After operation, vein grafts were harvested at third day for immunohistochemical, RT-PCR and Western blotting analysis of exogenous gene expression and for observation of thrombus formation by pathological method and scanning electron microscopy. At 30th days, the patency rate was recorded by vessel Doppler ultrasonography. RESULTS: Human TFPI mRNA and protein were detected in TFPI gene transferred vein grafts. Thrombosis was found in 8 animals of empty plasmid control group and in 7 animals of empty control group, but in only 1 of the TFPI group (P<0.05). Thirty days after operation, 5 vein grafts were occluded in both empty plasmid control group and empty control group, but none of vein grafts were occluded in TFPI group (P<0.05). The endothelial surfaces of the vein grafts in both control groups were covered with aggregated erythrocytes and platelets, but not in TFPI group. CONCLUSION: Human tissue factor pathway inhibitor gene transfection reduces thrombus formation and improves early patency rate in vein grafts. 相似文献