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  • Author or Editor: L. W. Rippetoe x
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Abstract

A computer-controlled temperature chamber system using modified chest-type freezers was developed for plant chilling studies. A temperature range of −18° to 35° ± 1.25°C enabled the system to be used for cold hardiness research. Chambers were easily modified for accurate control of soil temperature of container-grown plants. This system provided flexibility of use and regulation of several temperature regimes simultaneously at a comparatively low cost.

Open Access

Abstract

The effectiveness of intermittent and constant microsprinkler irrigation, compared with no irrigation, for freeze protection of young ‘Hamlin’ orange trees [Citrus sinensis (L.) Osb.], was studied during radiative and advective freezes in 198586. All tree trunks were wrapped with fiberglass insulation to reduce evaporative cooling. Intermittent irrigation of 5 min on and 10 or 15 min off maintained trunk temperatures under the wrap above critical values during radiative and advective freezes at air temperatures of — 7.1°C. However, trunk temperatures above the wrap decreased to below air temperatures due to evaporative cooling when using intermittent treatments during advective conditions. Trunk temperatures were highest for constant irrigation, intermediate for intermittent, and lowest for unirrigated wrapped trees; yet, survival was similar for all treatments. Nevertheless, intermittent irrigation provided acceptable freeze protection to the lower trunk using one-fourth as much water as constant irrigation and may allow citrus growers more flexibility in using irrigation for freeze protection of young citrus trees.

Open Access