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不同种植密度下的棉田小气候特点 总被引：2，自引：0，他引：2
为研究种植密度对田间小气候的影响,2008年在南疆阿克苏试验点,通过大田试验对不同种植密度下(9.0、13.5、18、22.5、27.0万株/hm2)棉田群体冠层不同层次的温度、空气相对湿度、土壤水分等要素进行了测定。结果表明:在所设置的密度范围内,棉花的株高在55～75cm,并且随密度增加株高降低;而茎粗、株宽、叶宽、果枝数等也有类似趋势。花期和吐絮期,棉花宽窄行的冠层空气温度均较高,最高均超过了31℃,并随当日时间先升后降,窄行温度高于宽行,冠层40cm处高于20cm处。相对湿度符合开口向上抛物线模型,花期较高且变化较小,中午时段最低只有40%,比见絮期高10个百分点以上;各处理以中间密度的相对湿度最为稳定,变化最小。土壤水分方面,密度小的处理地表蒸发严重,密度大的叶片蒸腾较多,因此,密度适中的处理土壤水分保持较好,变化范围较小。土壤15cm处地温,前期密度大的处理地温较高,中期受叶片遮荫影响而下降,但后期高密度处理温度又会升高,不过处理间差异不大,最高相差不过1℃。 相似文献
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Comparison of milk production of dairy cows kept in cold and warm loose-housing systems 总被引：2，自引：0，他引：2
A retrospective cohort study was conducted to test whether the lactation curves of cows kept in cold loose-housing systems (CLHs) were the same as for cows in warm loose-housing systems (WLHs) in the Nordic countries. Approximately 40 000 test-day records from 5366 Ayrshire or Black and White cows kept on 38 CLHs and 166 WLHs in Finland during 1996 and 1997 were used. Analysis used a random-coefficient model (correcting for parity, breed and calving-year-season and the correlation-structure between test-days of the same cow and cows of the same herd). Cows in a CLH produced up to 1 l less milk per test-day, but this difference was not statistically significant. Surprisingly, the difference in milk yield was not affected by calving-year-season, parity or breed. 相似文献
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The purpose of this study is to simulate urban micro-climate change due to the variation of wind flow and temperature assuming situations before and after applying programs using urban infrastructure regeneration technologies (UIRTs), and to then quantitatively estimate effectiveness on the urban regeneration schems. UIRTs focus on improving the recycling efficiencies of reclaimed water and biogas produced and to enforce the linkage among all environmental infrastructures associated with water, waste, and energy in an urban block. To implement the micro-climate analyses, data such as land use, topography, building height and materials, and weather conditions were collected, and the results estimated based on fluid simulations of cold wind and temperature variation pathways. There were three programs used in the urban regeneration project in J city: river restoration, traditional market revitalization, and a primary school eco-school. The height of cold wind from the ground level was significantly elevated, and the maximum wind velocity differential between before and after increased by 0.12 m/s due to the expansion of the waterfront space and grassland through the three programs. Overall, a temperature at the ground level dropped by 1.6 °C. Based on these results, the three programs improved the urban environment at ground level, and might ultimately be capable of diminishing the urban heat island effect and mitigating the energy consumption of urban areas. 相似文献
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灌溉与秸秆覆盖条件下冬小麦农田小气候特征 总被引：20，自引：0，他引：20
采用四种灌溉方式和有无秸秆覆盖的组合处理，研究了灌溉与秸秆覆盖结合条件下冬小麦农田的小气候特征。结果表明，从2月份开始，覆盖处理在14:00时的土壤温度明显低于不覆盖处理。秸秆覆盖能够降低近地面空气湿度和提高近地面空气温度，在灌溉条件下表现尤为明显。灌溉能够降低近地面的湍流交换系数和湍流热通量，提高潜热通量，而秸秆覆盖的作用相反。秸秆覆盖具有增强灌溉水入渗能力的作用。秸秆覆盖显著降低冬小麦的产量和水分利用效率(WUE)。 相似文献
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沿淮地区无汛期塑料大棚小气候效应及高效种养模式 总被引：2，自引：1，他引：2
在阐述水涝灾害对沿淮地区社会经济发展影响和无汛期大棚高效种养意义的基础上,着重分析了本地区无汛期塑料大棚小气候效应,并提出了沿准地区无汛期大棚种植、大棚养殖和大棚混合种养的三类高效种养模式,为本地区农业避灾和社会经济进步提供思路和技术。 相似文献
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[目的]研究播期和混播比例对玉米-秣食豆群体内小气候的影响。[方法]以玉米和秣食豆为试验材料,按秣食豆与玉米同期播种和延后播种2个播期,玉米与秣食豆3个混播比例进行混播试验。[结果]混播时期对作物群体内散射光有显著影响,对总入射光、温度和相对湿度无显著影响。混播比例对群体内光照和温度、湿度影响显著,随秣食豆比例的增加,群体内各层次的总入射光和散射光均显著减少,温度减低,湿度增加;而且生育前期随秣食豆比例的增加,群体内温度显著降低,生育后期相对湿度显著增加。[结论]播期和混播比例对群体内小气候有显著影响。混作复合群体通过改变田间小气候,影响作物的生理活动。 相似文献
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本文以许昌市清潩河河岸带4种不同植被覆盖形成的小气候为研究对象,采用平行观测法和对比观测法相结合进行分析,初步得出以下结论：各植被覆盖类型内光照强度变化趋势一致,随演替阶段的升高而降低。 相似文献
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