Impacts of seasonal air and soil temperatures on photosynthesis in Scots pine trees (original) (raw)
Related papers
Tellus B, 2007
In earlier studies the seasonal dynamics of photosynthetic capacity in northern conifers has been explained as a slow response to the ambient temperature. We tested this concept with Scots pine (Pinus sylvestris L.). We analysed the seasonal dynamics of photosynthetic efficiency in Scots pine at the timberline in Finnish Lapland, and in a southern boreal forest in Southern Finland. The relationship between the daily photosynthetic efficiency and leaf temperature history was determined from continuous measurements of shoot CO 2 exchange. The shoot CO 2 exchange and photosynthetic efficiency showed similar seasonal patterns in the northern and in the southern locations, following daily mean temperature with a delay. The relationship between the temperature history and photosynthetic efficiency appeared to be near sigmoidal both in the northern and in the southern trees. The relationship was also consistent from year-to-year, thus the seasonal course of photosynthetic efficiency can be predicted accurately from the ambient temperature using a sigmoidal relationship. A rapid decrease of photosynthetic efficiency was observed when daytime temperature dropped below zero or frost had occurred in the previous night. The difference in the rate of acclimation of photosynthetic efficiency between the north and the south was small.
Planta, 1998
Photosynthetic CO 2 uptake, the photochemical eciency of photosystem II, the contents of chlorophyll and chlorophyll-binding proteins, and the degree of frost hardiness were determined in three-year-old Scots pine (Pinus sylvestris L.) trees growing in the open air but under controlled daylength. The following conditions were compared: 9-h light period (short day), 16-h light period (long day), and natural daylength. Irrespective of induction by short-day photoperiods or by subfreezing temperatures, frost hardening of the trees was accompanied by a long-lasting pronounced decrease in the photosynthetic rates of one-year-old needles. Under moderate winter conditions, trees adapted to a long-day photoperiod, assimilated CO 2 with higher rates than the short-day-treated trees. In the absence of strong frost, photochemical eciency was lower under shortday conditions than under a long-day photoperiod. Under the impact of strong frost, photochemical eciency was strongly inhibited in both sets of plants. The reduction in photosynthetic performance during winter was accompanied by a pronounced decrease in the content of chlorophyll and of several chlorophyll-binding proteins [light-harvesting complex (LHC)IIb, LHC Ib, and a chlorophyll-binding protein with MW 43 kDa (CP 43)]. This observed seasonal decrease in photosynthetic pigments and in pigment-binding proteins was irrespective of the degree of frost hardiness and was apparantly under the control of the length of the daily photoperiod. Under a constant 9-h daily photoperiod the chlorophyll content of the needles was considerably lower than under long-day conditions. Transfer of the trees from short-day to long-day conditions resulted in a signi®cantly increased chlorophyll content, whereas the chlorophyll content decreased when trees were transferred from a long-day to a short-day photoperiod. The observed changes in photosynthetic pigments and pig-ment-binding proteins in Scots pine needles are interpreted as a reduction in the number of photosynthetic units induced by shortening of the daily light period during autumn. This results in a reduction in the absorbing capacity during the frost-hardened state.
Frontiers in plant science, 2014
Understanding the seasonality of photosynthesis in boreal evergreen trees and its control by the environment requires separation of the instantaneous and slow responses, as well as the dynamics of light reactions, carbon reactions, and respiration. We determined the seasonality of photosynthetic light response and respiration parameters of Scots pine (Pinus sylvestris L.) in the field in southern Finland and in controlled laboratory conditions. CO2 exchange and chlorophyll fluorescence were measured in the field using a continuously operated automated chamber setup and fluorescence monitoring systems. We also carried out monthly measurements of photosynthetic light, CO2 and temperature responses in standard conditions with a portable IRGA and fluorometer instrument. The field and response measurements indicated strong seasonal variability in the state of the photosynthetic machinery with a deep downregulation during winter. Despite the downregulation, the photosynthetic machinery re...
PLANT PHYSIOLOGY, 2007
Temperature and daylength act as environmental signals that determine the length of the growing season in boreal evergreen conifers. Climate change might affect the seasonal development of these trees, as they will experience naturally decreasing daylength during autumn, while at the same time warmer air temperature will maintain photosynthesis and respiration. We characterized the down-regulation of photosynthetic gas exchange and the mechanisms involved in the dissipation of energy in Jack pine (Pinus banksiana) in controlled environments during a simulated summer-autumn transition under natural conditions and conditions with altered air temperature and photoperiod. Using a factorial design, we dissected the effects of daylength and temperature. Control plants were grown at either warm summer conditions with 16-h photoperiod and 22°C or conditions representing a cool autumn with 8 h/7°C. To assess the impact of photoperiod and temperature on photosynthesis and energy dissipation, plants were also grown under either cold summer (16-h photoperiod/7°C) or warm autumn conditions (8-h photoperiod/22°C). Photosynthetic gas exchange was affected by both daylength and temperature. Assimilation and respiration rates under warm autumn conditions were only about one-half of the summer values but were similar to values obtained for cold summer and natural autumn treatments. In contrast, photosynthetic efficiency was largely determined by temperature but not by daylength. Plants of different treatments followed different strategies for dissipating excess energy. Whereas in the warm summer treatment safe dissipation of excess energy was facilitated via zeaxanthin, in all other treatments dissipation of excess energy was facilitated predominantly via increased aggregation of the light-harvesting complex of photosystem II. These differences were accompanied by a lower deepoxidation state and larger amounts of b-carotene in the warm autumn treatment as well as by changes in the abundance of thylakoid membrane proteins compared to the summer condition. We conclude that photoperiod control of dormancy in Jack pine appears to negate any potential for an increased carbon gain associated with higher temperatures during the autumn season.
Plant, Cell & Environment, 1997
ABSTRACTRepeated measures analysis was used to evaluate the effect of long‐term CO2 enhancement on seasonal trends of light‐saturated rates of net photosynthesis (Asat) and stomatal conductance to water vapour (gsat) of 9‐year‐old loblolly pine (Pinus taeda L.) trees grown in a 2 × 2 factorial experimental design of nutrition and water. A significant interaction effect of CO2 and nutrition on mean Asat was observed for juvenile foliage. Also, juvenile foliage exposed to +350 μmol mol−1 CO2 had a higher rate of increase of Asat between late summer and early autumn. This would lead to a greater potential for recharging carbohydrate reserves for winter. Mature foliage was affected by COsat, water and nutrient treatments in two ways. First, Asat was significantly increased as a result of elevated CO2 in January, a period when stomatal conductance was only 47% of the maximum observed rate. Secondly, the rate of increase of Asat from winter to early spring was accelerated as a result of b...
Canadian Journal of Botany, 2002
Cotyledons of jack pine seedlings (Pinus banksiana Lamb.) grown from seeds were expanded at low temperature (5°C), and total Chl content per unit area of cotyledons in these seedlings was only 57% of that observed for cotyledons on 20°C-grown controls. Chl a/b ratio of 5°C-grown jack pine was about 20% lower (2.3 ± 0.1) than 20°C controls (2.8 ± 0.3). Separation of Chl-protein complexes and SDS-PAGE indicated a significant reduction in the major Chl a containing complex of PSI (CP1) and PSII (CPa) relative to LHCII 1 in 5°C compared to 20°C-grown seedlings. In addition, LHCII 1 /LHCII 3 ratio increased from 3.8 in control (20°C) to 5.5 in 5°C-grown cotyledons. Ultrastructurally, 5°C-grown cotyledons had chloroplasts with swollen thylakoids as well as etiochloroplasts with distinct prolamellar bodies. Based on CO 2 -saturated O 2 evolution and in vivo Chl a fluorescence, cotyledons of 5°C jack pine exhibited an apparent photosynthetic efficiency that was 40% lower than 20°C controls. Seedlings grown at 5°C were photoinhibited more rapidly at 5°C and 1200 µmol·m -2 ·s -1 than controls grown at 20°C, although the final extent of photoinhibition was similar. Exposure to high light at 5°C stimulated the xanthophyll cycle in cotyledons of both controls and 5°C-grown seedlings. In contrast to winter cereals, we conclude that growth of jack pine at 5°C impairs normal chloroplast biogenesis, which leads to an inhibition of photosynthetic efficiency.
Frontiers in Plant Science, 2014
We studied the photosynthetic activity of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst) in relation to air temperature changes from March 2013 to February 2014. We measured the chlorophyll fluorescence of approximately 50 trees of each species growing in southern Finland. Fluorescence was measured 1-3 times per week. We began by measuring shoots present in late winter (i.e., March 2013) before including new shoots once they started to elongate in spring. By July, when the spring shoots had achieved similar fluorescence levels to the older ones, we proceeded to measure the new shoots only. We analyzed the data by fitting a sigmoidal model containing four parameters to link sliding averages of temperature and fluorescence. A parameter defining the temperature range over which predicted fluorescence increased most rapidly was the most informative with in describing temperature dependence of fluorescence. The model generated similar fluorescence patterns for both species, but differences were observed for critical temperature and needle age. Down regulation of the light reaction was stronger in spring than in autumn. Pine showed more conservative control of the photosynthetic light reactions, which were activated later in spring and more readily attenuated in autumn. Under the assumption of a close correlation of fluorescence and photosynthesis, spruce should therefore benefit more than pine from the increased photosynthetic potential during warmer springs, but be more likely to suffer frost damage with a sudden cooling following a warm period. The winter of 2013-2014 was unusually mild and similar to future conditions predicted by global climate models. During the mild winter, the activity of photosynthetic light reactions of both conifers, especially spruce, remained high. Because light levels during winter are too low for photosynthesis, this activity may translate to a net carbon loss due to respiration. Citation: Linkosalo T, Heikkinen J, Pulkkinen P and Mäkipää R (2014) Fluorescence measurements show stronger cold inhibition of photosynthetic light reactions in Scots pine compared to Norway spruce as well as during spring compared to autumn. Front. Plant Sci. 5:264.
European Journal of Forest Research, 2016
The temperature dependence of photosynthetic parameters has been a focus of interest during recent years owing to its profound implications in the new climate scenario. Many studies have addressed the short-term responses of photosynthetic parameters to temperature change. Less attention has been given to the intraspecific variability in the biochemical parameters of photosynthesis in response to differences in growth temperature. This study explores the effects of winter harshness on the leaf traits of two evergreen tree species (Quercus ilex and Q. suber). Leaf mass per unit area (LMA) and the concentrations of fiber, nitrogen (N), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in both species throughout a temperature gradient. Several photosynthetic parameters [maximum carboxylation rate (V cmax), maximum light-driven electron flux (J max), day respiration rate (R d) and relative stomatal limitation to photosynthesis] were assessed by measuring leaf response curves of net CO 2 assimilation versus intercellular CO 2 partial pressure. LMA and structural carbohydrate concentrations increased with the decrease in winter temperatures, whereas N concentrations did not show definite patterns. Chlorophyll, soluble proteins, Rubisco, V cmax and J max declined with the decrease in winter temperatures, whereas R d at a set common temperature (25°C) was higher at colder sites. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates in cold environments is associated with a reduced N allocation to the photosynthetic machinery, which leads to reduced photosynthetic capacity.