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Physiological and spectral characterization of the effects of atmospheric carbon dioxide and tropospheric ozone on wheat and soybean cultivars grown under well-watered and restricted moisture conditions.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Physiological and spectral characterization of the effects of atmospheric carbon dioxide and tropospheric ozone on wheat and soybean cultivars grown under well-watered and restricted moisture conditions./
Author:	Leblanc, Eric.
Description:	1 online resource (319 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 60-12, Section: B.
Contained By:	Dissertations Abstracts International60-12B.
Subject:	Botany. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9920958click for full text (PQDT)
ISBN:	9780599202245

Physiological and spectral characterization of the effects of atmospheric carbon dioxide and tropospheric ozone on wheat and soybean cultivars grown under well-watered and restricted moisture conditions.
Leblanc, Eric.

Physiological and spectral characterization of the effects of atmospheric carbon dioxide and tropospheric ozone on wheat and soybean cultivars grown under well-watered and restricted moisture conditions. - 1 online resource (319 pages)

Source: Dissertations Abstracts International, Volume: 60-12, Section: B.

Thesis (Ph.D.)--University of Maryland, College Park, 1998.

Includes bibliographical references

Vegetative responses to elevated atmospheric carbon dioxide (CO 2) and tropospheric ozone (O3) have been extensively characterized for many agricultural crops. Generally, positive effects of elevated CO 2 concentrations may be partially or completely counteracted by high O3 concentrations. The objectives of these studies were to investigate the single and combined effects of realistic, near-future, levels of above-ambient CO2 (+150 μL L-1) and O3 (+35 ± 5 nL L-1) on wheat (Triticum aestivum) and soybean (Glycine max) cultivars grown under well-watered (WW) and restricted moisture (RM) conditions. Wheat was grown in open-top chambers during the spring of 1995 to 1997, while soybean was grown during summers from 1994 to 1997. In wheat, responses to air quality were generally similar under WW and RM conditions. Elevated CO2 enhanced photosynthesis (Pn) even with high O3 concentrations. Stomatal conductances (gs) were reduced by CO2 and O3, and even more when combined at high levels, which led to increases in leaf temperature (Tleaf), no changes in transpiration (E) rates, and increases in water-use efficiency (WUE). Intercellular CO2 concentrations (C i) increased much more from elevated CO2 than from O 3 from pre- to post-flowering. Damage to the photosynthetic apparatus from O3 was undetectable with chlorophyll fluorescence. Variations in chlorophyll a and b were not a sensitive indicator of air quality-induced stress. Leaf area index (LAI) was not significantly affected by the treatments; above ground biomass and yields were significantly reduced by high O3 conditions. Seed test weights, milling quality scores, and flour yields were reduced, while flour protein was increased by high O3 concentrations under WW conditions. In soybean, CO2 stimulated Pn regardless of the O3 level. Responses in gs, Tleaf, WUE, chlorophyll fluorescence, and chlorophyll contents were similar to those observed in wheat. LAI, biomass, and yields were reduced by high O3 conditions. High O3 increased seed protein and oleic acid (C18:1) contents, but decreased linolenic (C18:3) and linoleic(C18:2) acid contents. A partial least squares (PLS) model was investigated as a new approach to reduce the dimensionality of hyperspectral information while minimizing the loss of relevant variance. The PLS model proved useful in predicting physiological variations from spectral reflectance variables in soybean where coefficients of determination (R2s) exceeded 0.80; however, R2S for wheat were between 0.50 and 0.60, probably because of more limited ranges in physiological responses. The model could not differentiate canopies based on their responses to air quality possibly because of important yearly variations and other sources of variability. The PLS approach has potential applications in remote sensing and should undergo further testing.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9780599202245Subjects--Topical Terms:

516217
Botany.
Subjects--Index Terms:

Carbon dioxideIndex Terms--Genre/Form:

542853
Electronic books.

Physiological and spectral characterization of the effects of atmospheric carbon dioxide and tropospheric ozone on wheat and soybean cultivars grown under well-watered and restricted moisture conditions.
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245 1 0 $a Physiological and spectral characterization of the effects of atmospheric carbon dioxide and tropospheric ozone on wheat and soybean cultivars grown under well-watered and restricted moisture conditions.
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504 $a Includes bibliographical references
520 $a Vegetative responses to elevated atmospheric carbon dioxide (CO 2) and tropospheric ozone (O3) have been extensively characterized for many agricultural crops. Generally, positive effects of elevated CO 2 concentrations may be partially or completely counteracted by high O3 concentrations. The objectives of these studies were to investigate the single and combined effects of realistic, near-future, levels of above-ambient CO2 (+150 μL L-1) and O3 (+35 ± 5 nL L-1) on wheat (Triticum aestivum) and soybean (Glycine max) cultivars grown under well-watered (WW) and restricted moisture (RM) conditions. Wheat was grown in open-top chambers during the spring of 1995 to 1997, while soybean was grown during summers from 1994 to 1997. In wheat, responses to air quality were generally similar under WW and RM conditions. Elevated CO2 enhanced photosynthesis (Pn) even with high O3 concentrations. Stomatal conductances (gs) were reduced by CO2 and O3, and even more when combined at high levels, which led to increases in leaf temperature (Tleaf), no changes in transpiration (E) rates, and increases in water-use efficiency (WUE). Intercellular CO2 concentrations (C i) increased much more from elevated CO2 than from O 3 from pre- to post-flowering. Damage to the photosynthetic apparatus from O3 was undetectable with chlorophyll fluorescence. Variations in chlorophyll a and b were not a sensitive indicator of air quality-induced stress. Leaf area index (LAI) was not significantly affected by the treatments; above ground biomass and yields were significantly reduced by high O3 conditions. Seed test weights, milling quality scores, and flour yields were reduced, while flour protein was increased by high O3 concentrations under WW conditions. In soybean, CO2 stimulated Pn regardless of the O3 level. Responses in gs, Tleaf, WUE, chlorophyll fluorescence, and chlorophyll contents were similar to those observed in wheat. LAI, biomass, and yields were reduced by high O3 conditions. High O3 increased seed protein and oleic acid (C18:1) contents, but decreased linolenic (C18:3) and linoleic(C18:2) acid contents. A partial least squares (PLS) model was investigated as a new approach to reduce the dimensionality of hyperspectral information while minimizing the loss of relevant variance. The PLS model proved useful in predicting physiological variations from spectral reflectance variables in soybean where coefficients of determination (R2s) exceeded 0.80; however, R2S for wheat were between 0.50 and 0.60, probably because of more limited ranges in physiological responses. The model could not differentiate canopies based on their responses to air quality possibly because of important yearly variations and other sources of variability. The PLS approach has potential applications in remote sensing and should undergo further testing.
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