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首页> 外文期刊>Agricultural and Forest Meteorology >The effect of screened openings on greenhouse microclimate.
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The effect of screened openings on greenhouse microclimate.

机译：筛选的开口对温室小气候的影响。

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The use of screens to reduce insect entry into greenhouses has become a common practice in many countries. The screens act as a mechanical barrier that prevents migratory insects from reaching the plants, and thus reduce the incidence of direct crop damage and of insect-transmitted virus diseases. As a consequence, the need for pesticide application is reduced; growers can follow international mandatory regulations, and can use biological control agents as well as insect pollinators. The exclusion of very small insects is achieved by installing fine-mesh screens across the greenhouse openings. Since the porosity (ratio between open and total areas) of these screens is usually low, they impede ventilation and reduce light transmission. Therefore, it is important to determine their resistance to airflow and their optical characteristics, in addition to characterizing their effectiveness against insect entry. Studies in wind tunnels have shown that screens that generated a higher pressure drop for a given incident air velocity caused higher temperature and humidity within a greenhouse. The fine-mesh insect-proof screens reduce the discharge coefficient of the openings, and thus reduce the mean air velocity and turbulence level at the openings. The screens generate small eddies and increase the spectral decay rate of the turbulent flow, and, furthermore, they reduce the air velocities within the greenhouse, which results in higher temperature and humidity gradients there. These problems may be addressed by increasing the area of the openings in naturally ventilated greenhouses or by using forced ventilation. When ventilation does not provide the desired air temperature, artificial cooling systems, such as fan and pad or fogging systems, need to be applied to maintain conditions favorable to plant growth. The present review examines the current literature on the use of insect-proof screens in greenhouses. It summarizes methods for characterizing the pressure drop through screens and screened openings, and examines the effect of screens on the microclimates of greenhouses and screenhouses. Differences among the various studies are discussed and directions for further research are suggested..
机译：在许多国家，使用屏风减少昆虫进入温室已经成为一种普遍做法。筛网充当机械屏障，可防止昆虫迁徙到植物中，从而减少直接农作物损害和昆虫传播的病毒疾病的发生。结果，减少了对农药施用的需求;种植者可以遵守国际强制性法规，并且可以使用生物防治剂以及昆虫授粉剂。通过在温室开口处安装细网状的筛网，可以排除非常小的昆虫。由于这些屏幕的孔隙率（开口面积与总面积之间的比率）通常较低，因此它们会阻碍通风并降低透光率。因此，除了表征其对昆虫进入的有效性外，重要的是确定它们的气流阻力和光学特性。对风洞的研究表明，对于给定的入射空气速度，产生更高压降的滤网会导致温室内更高的温度和湿度。细孔防虫网降低了开口的排放系数，从而降低了开口处的平均风速和湍流水平。滤网产生小的涡流并增加了湍流的光谱衰减率，此外，它们降低了温室内的空气流速，从而导致了那里较高的温度和湿度梯度。这些问题可以通过增加自然通风温室的开口面积或使用强制通风来解决。当通风不能提供所需的空气温度时，需要使用人工冷却系统（例如风扇和护垫或雾化系统）来维持有利于植物生长的条件。本综述审查了有关在温室中使用防​​虫网的最新文献。它总结了表征筛网和筛网开口压降的方法，并研究了筛网对温室和筛房微气候的影响。讨论了各种研究之间的差异，并提出了进一步研究的方向。

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