The effect of gibberellic acid on the response of leaf extension to low temperature

Helen J. Ougham, A. D. Tomos, A. D. Farrell

Research output: Contribution to journalArticlepeer-review

6 Citations (SciVal)

Abstract

The effect of cooling on leaf extension rate (LER) and on relative elemental growth rate (REGR) was measured in both gibberellic acid (GA)-responsive dwarf barley and in the same barley variety treated with GA. Seedlings were maintained at 20 °C while their leaf extension zone (LEZ) temperature was reduced either in steps to −6 °C in short-term cooling experiments, or to 10 °C for 48 h in long-term cooling experiments. Short-term cooling resulted in a biphasic response in LER, with a clear inflection point identified. Below this point, the activation energy for leaf extension becomes higher. The short-term response of LER to cooling was altered by the application of GA, which resulted in a lower base temperature (Tb), inflection point temperature and activation energy for leaf extension. Both GA-treated and untreated seedlings were less sensitive to cooling maintained for a prolonged period, with LER making a partial recover over the initial 5 h. Although long-term cooling reduced maximum REGR, it resulted in a longer LEZ and an increase in the length of mature interstomatal cells in GA-treated and untreated seedlings. These changes in overall physiology appear to enhance the ability of the leaves to continue expansion at suboptimal temperatures. In both GA-treated and cold-acclimated tissue, the occurrence of a longer LEZ was associated with a lower temperature sensitivity in LER.
Original languageEnglish
Pages (from-to)1329-1337
Number of pages9
JournalPlant, Cell and Environment
Publication statusPublished - 28 Apr 2006

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