Abstract This work evaluates roles and interactions of ground albedo (ag) and canopy architecture in capturing solar radiation inside Mediterranean greenhouses. Both incident and reflected solar radiation were measured over the ground surface and the greenhouse roof cover during a series of greenhouse experiments where common types of mulch and crop architecture were combined. In the experiments without crop around winter, changes in the daily mean ag from 0.06 to 0.38 induced changes in the greenhouse cover albedo (ac), which ranged from about 0.20 to 0.42. In measurements carried out around winter, both the ag and ac decreased when the ratio of the outdoor diffuse-to-solar radiation increased, independently of the ground surface, indicating that a higher percentage of solar radiation was trapped by the greenhouse under diffuse than under sunny conditions. In crops grown horizontally (not vertically trained), the effect of ground mulching over ag vanishes progressively with the increase in leaf area of the crops, resulting in an asymptotic trend of ag close to 0.23 at full ground covering, independently of the mulch type. In crops grown with high-wire production systems (plants grown in separated rows with the canopy distributed vertically up to 1.5–4.0 m high), asymptotic ag values were also reached but they were lower and dependent on the mulch type and the canopy architecture (0.08 for with black mulch and 0.12 to 0.19 with a gravel mulch). Then, crops with high-wire production systems, common in greenhouses, presented a higher efficiency in trapping solar radiation inside greenhouses. A model, which predicts fairly well the ac from the knowledge of ag and the cover shortwave reflectance, was proposed and used.

中文翻译：

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覆盖物和树冠结构如何相互作用以捕获地中海温室内的太阳辐射

摘要 这项工作评估了地面反照率 (ag) 和树冠结构在捕获地中海温室内的太阳辐射方面的作用和相互作用。在一系列温室实验中，在地表和温室屋顶覆盖物上测量了入射和反射的太阳辐射，其中结合了常见类型的覆盖物和作物结构。在冬季前后没有作物的实验中，每日平均 ag 从 0.06 到 0.38 的变化引起温室覆盖反照率 (ac) 的变化，范围从约 0.20 到 0.42。在冬季前后进行的测量中，当室外漫射与太阳辐射的比率增加时，ag 和 ac 均下降，与地表无关，表明在漫射条件下比在阳光充足的条件下被温室捕获的太阳辐射的百分比更高。在水平生长的作物（未垂直训练）中，地面覆盖对 ag 的影响随着作物叶面积的增加而逐渐消失，导致 ag 在完全地面覆盖时的渐近趋势接近 0.23，与覆盖类型无关。在采用高线生产系统种植的作物（植物分行种植，树冠垂直分布高达 1.5-4.0 m 高）中，也达到了渐近 ag 值，但它们较低并且取决于覆盖物类型和树冠结构（ 0.08（黑色覆盖物）和 0.12 至 0.19（砾石覆盖物）。然后，在温室中常见的具有高线生产系统的作物，在温室内捕获太阳辐射的效率更高。提出并使用了一个模型，该模型根据 ag 和覆盖短波反射率的知识很好地预测了 ac。