Abstract
Using a rapid spectrographic method of carbon dioxide measurement previously described by McAlister (1937) further studies on the time course of photosynthesis in the higher plant, wheat, variety Marquis, are herein reported. Of major importance in this work is the discovery of a pick-up of carbon dioxide in darkness immediately following a high rate of photosynthesis (see Figs. 3 and 4). This pick-up is believed to be due to the action of a carbon dioxide-combining intermediate; i.e., the "acceptor molecule" for carbon dioxide in photosynthesis. The conditions under which this phenomenon has so far been observed indicate that the intermediate is formed in relatively large quantities during the actual process of photosynthesis and not before. That the intermediate is chlorophyllous in nature is suggested by a simple stoichiometry of the order of unity that is found to exist between the number of carbon dioxide molecules taken up and the total number of chlorophyll molecules present in the plant. This is in opposition to the idea of a large photosynthetic unit of some 2000 chlorophyll molecules operating together in the reduction of 1 carbon dioxide molecule. Further studies of the induction phase under various conditions of previous dark rest and of carbon dioxide and light limitation are herein described. Employing the simple hypothesis that the number of carbon dioxide molecules not reduced during the induction period (induction loss) gives a measure of the number of elementary photosynthetic cycles unoperative or compensated for during induction together with the experimental fact that this induction loss is of the order of the total number of chlorophyll molecules present, these latter studies also indicate, in a less direct manner, that chlorophyll participates in photosynthesis as an individual molecule and not as part of a very large multimolecular chlorophyll unit. The fast dark reaction lasting about 1 minute (Fig. 7) required to reproduce both (a) the phenomena of induction in carbon dioxide assimilation and (b) the recovery of fluorescence of chlorophyll in leaves in darkness as observed by Franck and Wood (1936), demonstrates a close relationship between the fluorescence of chlorophyll and induction in photosynthesis. The rate of respiration (carbon dioxide production) of the higher plant, wheat, was measured under intense illumination and in the absence of carbon dioxide (to suppress assimilation). This value was found to be identical with the dark respirational rate measured before and after the light period, indicating very positively the absence of any direct effect of light on respiration.
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Claims 6
Claim · model-written summary
Wheat showed a pick-up of carbon dioxide in darkness immediately after a high rate of photosynthesis
- Taxon
- wheat
Triticum aestivume0 - Material
- variety Marquise0
- Outcome
- a pick-up of carbon dioxide in darknesse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the higher plant, wheat, variety Marquis”
e1“a pick-up of carbon dioxide in darkness immediately following a high rate of photosynthesis”
Claim · model-written summary
Carbon dioxide taken up and total chlorophyll molecules stood in a stoichiometry of the order of unity
- Taxon
- wheatTriticum aestivume0
- Outcome
- simple stoichiometrye1
- Value
- of the order of unitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the higher plant, wheat, variety Marquis”
e1“a simple stoichiometry of the order of unity that is found to exist between the number of carbon dioxide molecules taken up and the total number of chlorophyll molecules present in the plant”
Claim · model-written summary
The induction loss was of the order of the total number of chlorophyll molecules present
- Taxon
- wheatTriticum aestivume0
- Outcome
- induction losse1
- Value
- of the order of the total number of chlorophyll moleculese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the higher plant, wheat, variety Marquis”
e1“this induction loss is of the order of the total number of chlorophyll molecules present”
Claim · model-written summary
Chlorophyll fluorescence and induction in photosynthesis showed a close relationship
- Taxon
- wheatTriticum aestivume0
- Compound
- chlorophylle1
- Outcome
- close relationship between the fluorescence of chlorophyll and induction in photosynthesise1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the higher plant, wheat, variety Marquis”
e1“demonstrates a close relationship between the fluorescence of chlorophyll and induction in photosynthesis”
Claim · model-written summary
The intermediate for carbon dioxide fixation is suggested to be chlorophyllous in nature
- Taxon
- wheatTriticum aestivume0
- Outcome
- intermediate is chlorophyllous in naturee1
- Qualifier
- a simple stoichiometry of the order of unitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the higher plant, wheat, variety Marquis”
e1“That the intermediate is chlorophyllous in nature is suggested by a simple stoichiometry of the order of unity”
Claim · model-written summary
Respiration of wheat under intense illumination was identical to the dark respiration rate
- Taxon
- wheatTriticum aestivume1
- Treatment
- intense illuminatione1
- Outcome
- rate of respiratione1
- Direction
- identicale2
- Comparator
- dark respirational ratee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in the higher plant, wheat, variety Marquis”
e1“The rate of respiration (carbon dioxide production) of the higher plant, wheat, was measured under intense illumination and in the absence of carbon dioxide”
e2“This value was found to be identical with the dark respirational rate measured before and after the light period”
The same questions in other papers
light · physiology: respiration · Triticum aestivum (wheat)Results agree
1 paper in the same direction as this paper
- no effect
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.