QBARS - v32n1 Temperature Control in the Rooting Medium During Propagation (Summary)

Temperature Control in the Rooting Medium During Propagation
D. N. Whalley and R. E. Randall
Glasshouse Crops Research Institute, Littlehampton, Sussex
In: Ann. Appl. Biol. (1976) 83:305-309
Reprinted from Ornamentals Northwest, Dr. James Green, Editor

Article includes equipment description and advantages of using electronic temperature controllers with thermistor or semiconductor sensors and comparison with traditional electromechanical sensors, such as rod thermostats, for control of rooting medium temperature. The electronic controllers, now commercially available and proven reliable in commercial nursery operations, are very sensitive, contain no moving parts, contain sensors that may be placed adjacent to plant leaves or roots without altering the local microclimate while the associated controller can be mounted away from the propagating areas to facilitate maintenance and protection, and utilize rapid response sensors that are readily replaced.
With rhododendron cuttings a greater amount of rotting was noted as the temperature increased. Large numbers of cuttings were removed because of rotting during the experiment. he percentage survival values (not rooting values) as a mean of all three varieties were as follows: 15° C, 94%; 20° C, 70%; 25° C, 38%.