Computer modeling was used to study the effect of container volume and shape on summer temperature patterns for black polyethylene nursery containers filled with a 4 pine bark: 1 sand (v/v) rooting medium and located in Phoenix, Ariz. (lat. 33.5°N, long. 112°W) or Lexington, Ky. (lat. 38.0°N, long. 84.4°W). For both locations, medium temperatures were highest at the east and west container walls, halfway down the container profile, regardless of container height (20 to 50 cm) or volume (10 to 70 liters). The daily maximum medium temperature (Tmax) at the center was lower and occurred later in the day as container volume was increased because of an increased distance to the container wall. For both locations, predicted temperature patterns in rooting medium adjacent to the container wall decreased as the wall tilt angle (TA) increased. Predicted temperature patterns at the center of the container profile were lowered in response to the interaction of increased container height and wall TA. As container height decreased, the container wall TA necessary to lower center Tmax to ≤ 40C increased; however, the required increase in TA was greater for Phoenix than for Lexington, principally because of higher ambient air temperatures.
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