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Chemical Properties of Tobacco Leaves as Affected by Carbon Dioxide Depletion and Light Intensity 1
Author(s) -
Raper C. David,
Weeks W. W.,
Downs R. J.,
Johnson W. H.
Publication year - 1973
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1973.00021962006500060042x
Subject(s) - carbon dioxide , chemistry , nicotiana tabacum , horticulture , starch , nutrient , light intensity , carbohydrate , botany , food science , biology , biochemistry , physics , organic chemistry , gene , optics
Abstract Plants growing in controlled‐environment rooms are frequently subjected to self‐depleted CO 2 levels that manufacturers' “make‐up air systems” do little to alleviate. Flue‐cured tobacco ( Nicotiana tabacum L. ‘Coker 319’) rapidly depletes CO 2 from a 400 ppm (μl/liter) ambient level of 200 ppm. When compared with plants grown to maturity in an atmosphere continually adjusted to the 400 ppm level by supplementary CO 2 , chemical assays of leaf constituents indicated lesser effects of the CO 2 depletion than anticipated. The contents of starch, soluble carbohydrates, and polyphenolics were meagerly depressed in a CO 2 ‐depleted atmosphere. A reduction in light intensity below 322 hectolux had a greater effect accumulation of these compounds than did CO 2 depletion, The CO 2 depletion did affect the composition of the soluble carbohydrate fraction in leaf tissue. The CO 2 and light treatments in this experiment were continued until au advanced stage of leaf senescence. Both CO 2 depletion and reduced light intensities prolonged the growth period of leaves before the onset of senescence. We conclude that the extended period of growth, as well as the chronological timing of other morphological eve:ats, explains many of our reported results.