Thermal acclimation of photosynthesis and respiration in Pinus radiata and Populus deltoides to changing environmental conditions [article]

Lai Fern Ow, University Of Canterbury
Although it has long been recognized that physiological acclimation of photosynthesis and respiration can occur in plants exposed to changing environmental conditions (e.g. light, temperature or stress), the extent of acclimation in different tissues (i.e. pre-existing and new foliage) however, has not received much attention until recently. Furthermore, few studies have investigated the extent of photosynthetic and respiratory acclimation under natural conditions, where air temperatures vary
more » ... temperatures vary diurnally and seasonally. In this study, the effects of variations in temperature on respiratory CO2 loss and photosynthetic carbon assimilation were examined under both controlled and natural environments. The purpose of the investigations described in this thesis was to identify the effects acclimation would have on two key metabolic processes in plants exposed to temperature change, with emphasis also placed on the role of nutrition (nitrogen) and respiratory enzymatic characteristics on the potential for acclimation in two contrasting tree species, Pinus radiata and Populus deltoides. Controlled-environment studies (Chapter 2 and 3) established that rates of foliar respiration are sensitive to short-term changes in temperature (increasing exponentially with temperature) but in the longer-term (days to weeks), foliar respiration acclimates to temperature change. As a result, rates of dark respiration measured at any given temperature are higher in cold-acclimated and lower in warm-acclimated plants than would be predicted from an instantaneous response. Acclimation in new foliage (formed under the new temperature environment) was found to result in respiratory homeostasis (i.e. constant rates of foliar respiration following long-term changes in temperature, when respiration is measured at the prevailing growth temperature). Available evidence suggests that substantial adjustments in foliar respiration tend to be developmentally dependent. This may in part explain why respiratory homeostasis was only observed in new but no [...]
doi:10.26021/6931 fatcat:x433cdzkurfr7dqgd56ux7idba