The effect of local cooling on growth and water content of plants.

Abstract

In maize cv. Pioneer 395 grown in controlled environment in Hoagland solution at 20 deg C with 18-h photoperiods, low-temperature treatment of localized parts of the plant inhibited leaf elongation to an extent dependent on the site of cooling. Root temperatures of 5 deg C decreased leaf elongation as a result of water shortage and consequent retardation of cell extension. Plant osmotic potential increased and leaf elongation then resumed. When roots were cooled rapidly to 2-2.5 deg C the lower leaves died as a result of irreversible wilting, but with slow cooling the leaves survived. The response to these low temperatures was considerably less in older than in younger plants. Low temperatures at leaf meristem level directly reduced leaf elongation by acting on cell division and cell extension; the effect tended to increase with time. Local cooling above the meristem temporarily retarded growth by inhibiting carbohydrate translocation (demonstrated using 14CO2), but resulted in an increased concentration gradient which partly offset the effect of temperature. Cell extension was considerably inhibited, cell division probably only slightly. (Abstract retrieved from CAB Abstracts by CABI’s permission)