Diurnal and seasonal variations in gas exchange and water relations of lowland and upland black spruce ecotypes

1995 ◽  
Vol 73 (5) ◽  
pp. 716-722 ◽  
Author(s):  
Abdenbi Zine El Abidine ◽  
James D. Stewart ◽  
André P. Plamondon ◽  
Pierre Y. Bernier
Keyword(s):  
Gas Exchange ◽  
Environmental Factors ◽  
Water Relations ◽  
Picea Mariana ◽  
Black Spruce ◽  
Net Photosynthesis ◽  
Atmospheric Conditions ◽  
Mature Trees ◽  
Ecotypic Differentiation ◽  
Seasonal Responses

Gas exchange and water relations were measured on seedlings from two pairs of upland and lowland black spruce (Picea mariana (Mill.) BSP) populations. The seedlings were planted under natural atmospheric conditions in exterior sand beds. Measurements were carried out on eight separate days during the summer of 1992. Diurnal and seasonal responses of gas exchange and water relations parameters to natural changes in environmental factors were analyzed for possible ecotypic differences. Differences were found among the four populations and within one of the two upland–lowland pairs. However, no differences could be linked significantly to an upland–lowland ecotypic differentiation. The physiological responses are discussed with respect to diurnal and seasonal changes in environmental factors and to similarities with results from an earlier experiment involving mature trees from the same four populations. Key words: Picea mariana, water stress, net photosynthesis, stomatal conductance.

Gas exchange and water relations responses to drought of fast- and slow-growing black spruce families

1997 ◽  
Vol 75 (10) ◽  
pp. 1700-1706 ◽  
Author(s):  
Weixing Tan ◽  
Terence J. Blake
Keyword(s):  
Growth Rate ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Soil Water ◽  
Water Relations ◽  
Picea Mariana ◽  
Black Spruce ◽  
Turgor Pressure ◽  
Fast Growing ◽  
Slow Growing

To determine how different mechanisms of drought tolerance contribute to growth rate under drought, this study compared four full-sib black spruce (Picea mariana (Mill.) B.S.P.) families which differed in growth rate when soil water became limiting, stomatal conductance, photosynthesis, and water relations responses to drought. Repeated drought cycles were imposed by withholding soil water in a nursery and physiological responses were measured near the end of the first and third cycle. The most vigorous family under drought had greater osmotic adjustment and maintained higher rates of net photosynthesis during the first cycle of drought and resumed higher rates of photosynthesis sooner upon stress relief, compared with two slow-growing families. Pressure–volume analysis of drought-stressed shoot tissues indicated that the fast-growing family exhibited a larger degree of elastic enhancement (i.e., decrease in bulk modulus of elasticity), which would explain its higher turgor pressure, compared with the two less vigorous families. However, family differences in gas exchange and water relations largely diminished when seedlings were exposed to repeated cycles of drought. Therefore, fast-growing black spruce families under drought may gain selective growth advantage by a better ability to tolerate, rather than postpone, momentary dehydration. Short-term screening trials could be used to detect drought tolerant genotypes in black spruce. Key words: drought, family variation, photosynthesis, Picea mariana, stomatal conductance, water relations.

Design and testing of twig chambers for ozone fumigation and gas exchange measurements in mature trees

1994 ◽  
Vol 102 ◽  
pp. 541-546 ◽  
Author(s):  
Wilhelm M. Havranek ◽  
Gerhard Wieser
Keyword(s):  
Gas Exchange ◽  
Net Photosynthesis ◽  
Ambient Air ◽  
Field Conditions ◽  
Chamber System ◽  
Mature Trees ◽  
Diurnal Courses ◽  
Controlled Conditions ◽  
Design And Testing

SynopsisA twig chamber system was developed for the exposure of mature trees to ozone (O3) under field conditions. The fumigation system allowed the exact control of O3 concentrations in the chambers, the measurement of O3 uptake as well as gas exchange measurements under ambient and controlled conditions during and after O3 fumigation. Because of differences in individual twigs the system should provide the exposure of replicates to different O3 treatments. Tests showed that temperature, humidity and O3 concentrations inside the chambers were comparable with diurnal courses observed in the field. Comparative gas exchange measurements indicated that there were no differences in net photosynthesis and conductance of twigs outside the chambers and twigs which remained within the chambers for 23 weeks receiving ambient air.

Comparison of growth and physiology of layers and naturally established seedlings of black spruce in a boreal cutover in Quebec

1999 ◽  
Vol 29 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Raynald Paquin ◽  
Hank A Margolis ◽  
René Doucet ◽  
Marie R Coyea
Keyword(s):  
Water Potential ◽  
Picea Mariana ◽  
Black Spruce ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Height Growth ◽  
Total Height ◽  
Acclimation Period ◽  
Use Efficiency ◽  
Growth Of Seedlings

Growth and physiology of layers versus naturally established seedlings of boreal black spruce (Picea mariana (Mill.) BSP) were compared 15 years after a cutover in Quebec. During the first 8 years, height growth of seedlings was greater than that of layers, averaging 10.4 and 7.0 cm/year, respectively. For the last 5 years, annual height growth of layers and seedlings did not differ (25 cm/year; p > 0.05). Over the entire 15-year period, total height growth of seedlings (251 cm) was greater than that of layers (220 cm), although total height did not differ (p > 0.05) over the last 6 years. During the 15th growing season, there were no differences (p > 0.05) for predawn shoot water potential, stomatal conductance, net photosynthesis, intercellular to ambient CO2 ratio, water use efficiency, and hydraulic conductance between layers and seedlings. For diurnal shoot water potential, seedlings showed slightly less stress than layers on two of the four sampling dates. Thus, in the first few years following the cutover, the slower growth observed for layers indicated that they had a longer acclimation period following the cutover. Afterwards, similar height growth, total height, and physiological characteristics of the two regeneration types indicated that layers can perform as well as naturally established seedlings.

Water stress preconditioning of black spruce seedlings from lowland and upland sites

1994 ◽  
Vol 72 (10) ◽  
pp. 1511-1518 ◽  
Author(s):  
Abdenbi Zine El Abidine ◽  
Pierre Y. Bernier ◽  
James D. Stewart ◽  
André P. Plamondon
Keyword(s):  
Water Relations ◽  
Black Spruce ◽  
Sugar Content ◽  
Net Photosynthesis ◽  
Soil Drought ◽  
Drought Period ◽  
Gas Exchanges ◽  
Total Sugar Content ◽  
Net Photosynthesis Rate ◽  
One Year

One-year-old seedlings from two pairs of upland – lowland populations were subjected to three cycles of drought preconditioning. During a subsequent fourth cycle, preconditioned seedlings and seedlings that had been maintained under well-watered conditions were subjected to a final soil drought. During the drought periods, small but significant differences in gas exchanges and water relations were observed between upland and lowland seedlings but the differences were not consistent either within each lowland – upland pair or over the four cycles. During the final drought period, preconditioned seedlings maintained significantly higher net photosynthesis rate, stomatal conductance, and transpiration rate than unconditioned seedlings. In contrast, no significant differences were found in midday water potential, total sugar content, or water relations parameters between preconditioned and unconditioned seedlings. The results suggest an absence of ecotypic variation with respect to drought tolerance in black spruce. They also suggest that preconditioning in black spruce seedlings occurs mostly through the acclimation of stomatal and photosynthetic mechanisms to drought, without active osmotic adjustment. Key words: Picea mariana, ecotype, gas exchanges, water relations, osmoregulation, preconditioning.

Growth and ecophysiological responses of black spruce seedlings to elevated CO2 under varied water and nutrient additions

1993 ◽  
Vol 23 (6) ◽  
pp. 1033-1042 ◽  
Author(s):  
Kurt H. Johnsen
Keyword(s):  
Gas Exchange ◽  
Black Spruce ◽  
Seedling Emergence ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Pressure Potential ◽  
Foliar N ◽  
Nutrient Additions ◽  
Xylem Pressure Potential ◽  
Ecophysiological Responses

Two controlled-environment studies examined growth and ecophysiological responses of black spruce (Piceamariana (Mill.) B.S.P.) seedlings to elevated CO2 under varied water and nutrient additions. Growth analyses were conducted followed by measurements of gas exchange, xylem pressure potential and foliar N concentrations. Growth under elevated CO2 (700 ppm) increased final seedling dry weights by 20–48% compared with seedling growth under ambient CO2 (350 ppm). Percent increases in seedling dry weight were greater under drought versus well-watered conditions and higher versus lower nutrient additions. Seedlings grown under elevated CO2 displayed higher water use efficiency than seedlings grown under ambient CO2. This was apparent based upon instantaneous gas exchange as well as xylem potential pressure measurements. Elevated CO2-induced stimulation of relative growth rate was greatest shortly after seedling emergence and decreased with increased seedling size. Acclimation of net photosynthesis was observed and was reversible. Analyses using allometric principles indicate net photosynthetic acclimation resulted from: (i) growth-induced nutrient dilution; (ii) a decrease in foliar N levels not owing to dilution; and (iii) a decrease in net photosynthetic activity.

Effects of summer frosts and subsequent shade on foliage gas exchange in peatland tamarack and black spruce

1992 ◽  
Vol 22 (7) ◽  
pp. 973-979 ◽  
Author(s):  
Q. L. Dang ◽  
V. J. Lieffers ◽  
R. L. Rothwell
Keyword(s):  
Gas Exchange ◽  
Enhanced Recovery ◽  
Black Spruce ◽  
Net Photosynthesis ◽  
Recovery Phase ◽  
Detectable Effect ◽  
Mesophyll Conductance ◽  
Direct Sunlight ◽  
Two Phases ◽  
Freezing Chamber

In this study, we examined the effect of summer frost on light-saturated net photosynthesis (Pnet) and related parameters in 20-year-old black spruce (Piceamariana (Mill.) B.S.P.) and tamarack (Larixlaricina (Du Roi) K. Koch) at a peatland site in central Alberta. Summer frosts were simulated in the field using a self-contained freezing chamber. Some trees were shaded from direct sunlight after freezing. Shaded trees received about 20% of full sunlight at midday. We found that the response of photosynthesis consisted of two phases: a depression phase, where photosynthesis declined progressively, and a recovery phase, where photosynthesis recovered gradually. The length of the depression phase varied with species but not with the degree of freezing. For both species, depression in Pnet was primarily related to decreased mesophyll conductance to CO2, and a full recovery of Pnet took more than 11 days. Post-frost shade enhanced recovery in Pnet after a −3.5 °C frost in tamarack, but had no detectable effect after a −6 °C frost in tamarack or a −3 °C frost in black spruce.

Sign in / Sign up

Export Citation Format

Share Document