Influence of Water and Temperature Stress on the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination

Abstract

The temperature dependence of the rate and magnitude of the reappearance of photosystem 11 (PSII) variable fluorescence following illumination has been used to determine plant temperature optima. The present study was designed to determine the effect of a plant's environmental history on the thermal dependency of the reappearance of PSII variable fluorescence. In eter, the Michaelis constant (Kin), to define the limits of thermal stress (2, 8, 10, 11). These measures are used as indicators of metabolic efficiency. The TKWs have been identified for several crop species (1, 2, 4, 5). These TKWs are narrower than plant temperatures experienced on a seasonal or daily basis (2). When plants are at temperatures outside of their TKW, reduction in growth and development occurs (2). Maintenance of plant temperatures within the TKW is controlled, primarily, by transpirational cooling during the day. The plant has no capacity to increase its leaf temperature if ambient temperature is below the TKW. Thus, the ability of plants to maintain optimal temperature is directly dependent upon the available soil water stored in the soil volume.The information provided by the TKW has been used in characterizing the stress that field crops experience (2), comparing differences between and within crop species (4), improving irrigation management (13), and providing new approaches to improving a crop's thermotolerance (3). The time, expense, and facilities required to determine the TKW of a plant was a limitation to more general use, however. An alternative and rapid method for determining the optimum temperature of a plant was needed. Burke (1) suggested that a temperature-dependent Chl fluorescence measurement might be used to determine plant temperature optima. PSII variable fluorescence is routinely monitored in the leaves of plants that have been dark adapted for approximately 30 min (6, 7). The PSII Fv signal of these "dark adapted" leaves is near maximum for an individual leaf (7). Conversely, Fv of light-saturated leaves is close to zero. The technique used by Burke (1) was to monitor the time course of the reappearance of the Fv signal for leaves moved from the light and placed in the dark. The rate of Fv reappearance and the maximum Fv value reached was dependent on the temperature of the leaf during the dark incubation period (1). Using leaves from well-watered, laboratory grown plants, Burke (1) has demonstrated that the incubation temperature resulting in the optimum reappearance of PSII Fv directly corresponded with the temperatures within the TKW for seven plant species. The incubation temperature resulting in the optimal Fv reappearance was determined by comparing maximum Fv

Juvenile Rhus glabra leaves have higher temperatures and lower gas exchange rates than mature leaves when compared in the field during periods of high irradiance

“…Similar differences in gas exchange patterns during leaf development have been reported for numerous species (Choinski and Johnson, 1993;Choinski and Wise, 1998;Woodall et al, 1998;Choinski et al, 2003) in which juvenile, not fully expanded leaves had lower conductance and photosynthetic rates than mature leaves, on an equal leaf area basis. Although many studies have reported leaf temperature data on mature leaves under field conditions (Ansari and Loomis, 1959;Ferguson and Burke, 1991;Singsaas and Sharkey, 1998;Wise et al, 2004), this is the first report that shows leaf temperature data in both juvenile and mature leaves on the same plant in conjunction with anatomical data on stomatal development.…”

Optimal Thermal Environments for Plant Metabolic Processes (Cucumis sativus L.) (Light-Harvesting Chlorophyll a/b Pigment-Protein Complex of Photosystem II and Seedling Establishment in Cucumber)

“…A strong correlation between the temperatures delimiting the TKWs of wheat, cotton, bell pepper, and petunia and the thermal dependence of the reappearance of the variable component of PSII fluorescence in the dark following illumination has been reported previously (Burke, 1990;Ferguson et al, 1991). Because of the difference in TKW between that determined for NADH-hydroxypyruvate reductase in the present study and that reported previously for NADPHglutathione reductase (Mahan et al, 1990), we have used the fluorescence technique to further establish the bounds of the temperature optimum of cucumber.…”

“…Comparison of the thermal response of PSII fluorescence reappearance with the temperature sensitivity of the apparent K, of hydroxypyruvate reductase for NADH showed that temperatures providing maximal fluorescence reappearance corresponded with temperatures providing the minimum apparent K, , , values (Burke, 1990;Ferguson et al, 1991). The fluorescence technique not only provided a useful tool for the analysis of plant temperature optima, but also strengthened the TKW concept.…”

“…The TKW has been shown to be a reliable indicator of the temperature range outside of which plants experience temperature stress and reduced plant performance (Burke et al, 1988;Burke, 1990;Mahan et al, 1990;Ferguson et al, 1991). TKWs have been identified for severa1 crop species (Burke et al, 1988;Burke, 1990;Mahan et al, 1990;Ferguson et al, 1991), and have proven to be narrower than plant temperatures experienced on a seasonal or daily basis (Burke et al, 1988;Ferguson et al, 1991). Temperature extremes (for example, heat shock and chilling injury) are not required for a plant to experience thermal stress.…”

Genetic Diversity in the Environmental Conditioning of Two Sorghum (<i>Sorghum bicolor</i> L.) Hybrids

“…The purpose of the thermal kinetic window was to provide a general indicator of the range of temperatures in which the optimal temperature for metabolism was located. The best correlative evidence of the validity of the TKWs comes from the determination of the temperature dependence of the reappearance of photosystem II variable fluorescence following illumination [4] [5]. The chlorophyll fluorescence functions as a natural indicator of the in vivo temperature characteristics of the plant.…”