School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemChlorophyll fluorescence for rapid assessment of salt tolerance in eucalypts( 1999)Chlorophyll fluorescence parameters were investigated, using the OPTISCIENCES 0S5-FL fluorometer. for their potential as non-invasive rapid indices of salt stress in Eucalypts. Cloned E. camaldulensis and E. urophvlla x grandis plants were subjected to salinity (0-650mM NaCI) and chlorophyll fluorescence parameters measured. Dark-adapted and quenching parameters did not show consistent responses to salinity stress. The light-adapted parameter Fds, measured by the Yield program, showed a predictable trend in response to salinity treatment. Measurements were influenced by diurnal changes, positional effects and environmental changes. It is therefore important to measure Fd, within a controlled environment, randomising and rearranging plants during the course of the experiment. Fully expanded, green, attached leaves should be used for measurement and salt concentration should be raised slowly (e.g. 50mM/5 days) after a concentration of 300mM NaCI has been reached. Statistical analysis should be performed using non-parametric methods as chlorophyll fluorescence parameters are not normally distributed. In most cases Fds declines before the onset of visible physical symptoms, however it is affected by sudden shock. It is therefore important that results show a consistent decline in Fds and/or Fds decreases markedly (e.g. 40-50% of the control). This method allows for the objective ranking for salt tolerance of both seedlings and clones. Fds may also have the potential to detect individual responses to salinity and assist the detection of individuals with uncharacteristic responses or unsatisfactory root systems within clones.