Microhabitat comparisons of transpiration and photosynthesis in three subalpine conifers

1988 ◽  
Vol 66 (5) ◽  
pp. 963-969 ◽  
Author(s):  
Gregory A. Carter ◽  
William K. Smith
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Pinus Contorta ◽  
Photosynthetic Performance ◽  
Leaf Conductance ◽  
Forest Understory ◽  
Subalpine Forest ◽  
Abies Lasiocarpa ◽  
Use Efficiency ◽  
Central Rocky Mountains

Differences in water and photosynthetic relations were compared for three codominant conifers (Engelmann spruce (Picea engelmaniï), subalpine fir (Abies lasiocarpa), and lodgepole pine (Pinus contorta) at microhabitats within a subalpine forest (central Rocky Mountains, U.S.A.) that were considered representative of different successional stages. Diumal measurements of photosynthesis, leaf conductance, and transpiration were taken at microhabitats considered early-successional (open), intermediate (forest gap), and late-successional (forest understory) environments to evaluate possible influences of gas-exchange physiology in observed distributional and successional patterns. Pine had greater water-use efficiency (photosynthesis/transpiration) in early- versus late-successional environments, primarily as a result of a lower leaf conductance and transpiration. Photosynthetic performance was similar among all three species at each respective microhabitat and increased as the openness of the microhabitat increased. Greater water-use efficiency may significantly improve the growth of pine over spruce and fir on more open, drier sites at lower elevation. Higher transpiration in spruce and fir may limit these species to higher elevation sites, to understory sites at middle elevations, and to moister open sites at lower elevations (e.g., riparian sites).

Limitations to photosynthetic carbon gain in timberline Abies lasiocarpa seedlings during prolonged drought

2007 ◽  
Vol 37 (3) ◽  
pp. 568-579 ◽  
Author(s):  
Daniel M. Johnson ◽  
William K. Smith
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Water Status ◽  
Early Summer ◽  
Leaf Conductance ◽  
Carbon Gain ◽  
Forest Site ◽  
Abies Lasiocarpa ◽  
Photosynthetic Carbon ◽  
Use Efficiency

Photosynthesis, water status, and associated physiological parameters were measured in chronically drought-stressed seedlings (5 years of below-average precipitation, 107 cm net deficit) of Abies lasiocarpa (Hook.) Nutt. above (treeline ecotone site, TS) and below (forest site, FS) a Rocky Mountain timberline. In contrast to normal seasonal patterns reported for timberline conifer trees, xylem water potentials were exceptionally low in early summer and remained low for the rest of the summer. Although photosynthesis was not significantly different between the two sites, early season photosynthesis was greater than late-season photosynthesis, especially at FS. Mean daily values of leaf conductance to water vapor (gwv) and transpiration (E) were also low at the beginning of summer (gwv from 0.01 mol·m–2·s–1 to 0.13 mol·m–2·s–1 and E from 0.4 μmol·m–2·s–1 to 2.9 μmol·m–2·s–1) and continued to decrease through summer (an approximate 10-fold decrease in gwv and a 2-fold to 3-fold decrease in E), which resulted in increasing water-use efficiency as summer progressed. Although the slope of instantaneous photosynthesis – intercellular CO2 concentration curves was reduced (lower carboxylation efficiency) from July to September, the relative stomatal limitation to carbon gain was less than 50% over the entire measurement period. Mean daily intercellular CO2 concentrations decreased from near ambient levels (approximately 350–360 ppm) to 290 ppm over the course of summer. Overall, nonstomatal limitations appeared to have the largest impact on photosynthetic carbon gain, although seasonal decreases in leaf conductance and a corresponding depletion of intercellular CO2 indicated that there were also significant stomatal limitations to carbon gain that resulted in a continued regulation of greater water use efficiency.

Response of wheat growth and CO2 assimilation to altering root-zone temperature

1990 ◽  
Vol 68 (12) ◽  
pp. 2698-2702 ◽  
Author(s):  
S. H. Al-Hamdani ◽  
G. W. Todd ◽  
D. A. Francko
Keyword(s):  
Water Use Efficiency ◽  
Water Potential ◽  
Water Use ◽  
Root Zone ◽  
Soluble Sugar ◽  
Leaf Conductance ◽  
Assimilation Rate ◽  
Root Zone Temperature ◽  
Use Efficiency ◽  
Zone Temperature

Wheat plants (Triticum aestivum L. var. Chisholm) grown at an air temperature of 23 °C and a root-zone temperature of 3 °C exhibited a significant reduction in shoot and root dry weight and leaf area compared with plants grown at a root-zone temperature of 23 °C. This reduction was correlated with a significantly lower CO2 assimilation rate that was associated with lower leaf conductance, lower internal CO2 concentration, and more negative water potential. Low CO2 assimilation rate was also associated with high starch and total soluble sugar levels in the shoot, less translocation of photosynthate, and possibly less sink demand. Leaf chlorophyll concentration was not affected by altering the root-zone temperature, whereas water use efficiency of plants grown at a root-zone temperature of 3 °C was as much as 1.5 times higher as those grown at 23 °C. Key words: carbohydrate, chlorophyll, photosynthate partitioning, leaf conductance, water potential, water use efficiency.

Drought response of mesophyll conductance in forest understory species - impacts on water-use efficiency and interactions with leaf water movement

2014 ◽  
Vol 152 (1) ◽  
pp. 98-114 ◽  
Author(s):  
Robert Hommel ◽  
Rolf Siegwolf ◽  
Matthias Saurer ◽  
Graham D. Farquhar ◽  
Zachary Kayler ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Water Movement ◽  
Leaf Water ◽  
Forest Understory ◽  
Drought Response ◽  
Mesophyll Conductance ◽  
Understory Species ◽  
Use Efficiency

scholarly journals PHOTOSYNTHESIS AND TRANSPIRATION DURING GROWTH AND DEVELOPMENT OF ALLIUM CEPA L.

HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 263B-263
Author(s):  
Daniel Warnock ◽  
William Randle ◽  
Mark Rieger
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Allium Cepa ◽  
Growth And Development ◽  
Developmental Stages ◽  
Leaf Conductance ◽  
Short Day ◽  
Allium Cepa L ◽  
Use Efficiency ◽  
Inductive Photoperiod

Photosynthesis is the very essence of agriculture. Previous photosynthetic and transpirational studies of onion (Allium cepa) have been limited to specific developmental stages. Our study measured photosynthesis and transpiration in sixteen plants of a single short-day cultivar over an eleven week period containing both non- and bulb inductive photoperiods. Differences in weekly means for photosynthesis, leaf conductance, water use efficiency, and intercellular CO, were highly significant. Weekly photosynthetic means increased under a non-inductive photoperiod and peaked one week after initiating a bulb inducing photoperiod. A decrease and leveling period occurred as bulbs developed followed by a decrease as foliage lodged. Weekly photosynthetic and leaf conductance means were correlated and highly significant. Water use efficiency and intercellular CO, means remained fairly constant throughout the study suggesting that photosynthesis in unstressed onions was controlled by internal mechanisms instead of stomata.

Dark-adapted leaf conductance, but not minimum leaf conductance, predicts water use efficiency of soybean (Glycine max L. Merr.)

2013 ◽  
Vol 93 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Alison E. Walden-Coleman ◽  
Istvan Rajcan ◽  
Hugh J. Earl
Keyword(s):  
Glycine Max ◽  
Water Use Efficiency ◽  
Water Use ◽  
Leaf Conductance ◽  
Physiological Basis ◽  
Plant Water Use ◽  
Whole Plant ◽  
Glycine Max L ◽  
Use Efficiency ◽  
Soybean Leaves

Walden-Coleman, A. E., Rajcan, I. and Earl, H. J. 2013. Dark-adapted leaf conductance, but not minimum leaf conductance, predicts water use efficiency of soybean (Glycine max L. Merr.). Can. J. Plant Sci. 93: 13–22. The conductance to water vapor of dark-adapted leaves (gdark) has been shown to be negatively correlated with whole-plant water use efficiency (WUE) in soybean, but the physiological basis of this relationship is unknown. It is also not clear how gdark compares with the minimum leaf conductance of wilted leaves (gmin), a trait that has been studied extensively across a broad range of species. We compared gdark to gmin of soybean leaves and found that gdark values were consistently much higher than gmin values measured on the same leaves. Also, across seven soybean varieties known to differ for WUE, gdark but not gmin was correlated with WUE. Thus, gdark and gmin should be considered distinct traits. We measured gdark at two different leaf positions, and found that gdark measured at the lower leaf position (two main stem nodes below the youngest fully expanded leaf) was best correlated with WUE. We then used this method to screen a selection of current commercial soybean varieties adapted to Ontario, Canada, for variation in gdark. The range in gdark among the commercial varieties was as broad as that measured previously among more diverse genotypes, suggesting that Ontario soybean varieties might also vary widely for WUE.

Tree species effects on ecosystem water-use efficiency in a high-elevation, subalpine forest

Oecologia ◽  
2009 ◽  
Vol 162 (2) ◽  
pp. 491-504 ◽  
Author(s):  
Russell K. Monson ◽  
Margaret R. Prater ◽  
Jia Hu ◽  
Sean P. Burns ◽  
Jed P. Sparks ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Tree Species ◽  
High Elevation ◽  
Subalpine Forest ◽  
Species Effects ◽  
Ecosystem Water Use Efficiency ◽  
Tree Species Effects ◽  
Use Efficiency
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