Elevated Atmospheric CO2 Enhances Daily Carbon Export from Photosynthetic Source Organs and Thus Controls the Increased Growth of Vascular Plants, Tracheophytes
Bibliographic record
Abstract
Introduction Leaves of the higher vascular plants, tracheophytes, have two primary functions(1). First they serve as organs of C-fixation. Second they are major sources of assimilates for development of ‘sink’ tissues that also regulate plant growth potential especially at elevated- CO2 (EC). Methods A leaf is a heterogeneous structure exporting both in day and night. Organ and organism gas-exchanges and 14 C-analyses were integrated showing that quantitatively numerous C3, C3/C4-intermediate and C4 plants export mostly while light energy is trapped and more at EC. Results C4's fix and export more than C3’at ambient-CO2(AC). Interestingly, some C3's exporting assimilates, other than sucrose, have translocation rates that proportional to fixation are comparable to C4's. At EC, C3's achieve higher C-fixation rates, and C-export is comparable with C4's. Transition experiments between AC and EC, show that temporary acidification of the apoplast occurs but a brief perturbation of intercellular [H]+ ion levels correlates with only a temporary reduction in assimilate loading and 14 C-export. Export is reestablished and source-leaf-strength at EC is greater than AC supporting faster growth. Discussion Depending on the stage of canopy development, long-term acclimation to EC can result in a depression in single-leaf-photosynthesis, an observation that merely correlates to a more rapid turnover of key proteins, such as RUBISCO, that are signs of enhanced canopy maturation. Improving crop production necessitates a strategy that maximizes source to sink balance throughout the life-cycle. Recent studies, with transgenic lines of Arabidopsis thaliana , in which dark respiratory processes associated with pyruvate-flux were targeted (2,3) suggest that daily patterns of canopy photosynthesis, respiration and growth are enhanced at EC. EC not only enhances the metabolism of the (laminar) rosette leaves, but also that of the non-laminar photosynthetic organs (e.g., stems and branches of the inflorescence) that by the time of seed filling can supply over 90% of daily-C-fixed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".