Investigation into the effects of self-pollination on pseudotsuga menziesee (mirb.) franco
Bibliographic record
Abstract
Extensive investigations have shown that the genetic systems which prevent self-fertilization in many of the Angiosperms are based upon the incompatibility of pollen and style. Past studies have also shown that many of the Gymnosperms, including Pseudotsuga, produce little or no viable seed after self-pollination. The causes of this seed failure, however, had not been determined. It was considered that a cytological study of development within the ovules after the self-pollination of Pseudotsuga menziesii should show whether seed failure was caused by comparable incompatible systems. Controlled self- and cross-pollinations were accordingly made on two trees at Vancouver in 1952 and on three trees each, at Victoria and Lake Cowichan in 1954. Cone samples from both pollinations were removed at various dates from each tree and the ovules embedded for later sectioning. The remaining cones were collected at maturity and the seed extracted. It was found that the yields of viable seed varied greatly in individual trees and the investigation was accordingly divided into two parts. The cytological study was confined to two of the trees which had produced very little viable seed after selfing. The second part of the investigation was concerned with the effect of self-pollination on the progeny. The cytological study showed that neither germination of the pollen nor its subsequent development until the time of syngamy were in any way inhibited and both compared favourably with development in the ovules from cross-pollinated cones. Proembryo formation and early embryonic development were normal but the embryos in both trees collapsed approximately ninety days after self-pollination. This collapse appeared to be caused by some failure in the vital relationship between the young embryos and their surrounding gametophytes. The latter appeared healthy and comparable in every respect with those in which embryos from cross-pollination were growing vigorously. It is considered that embryo collapse after self-pollination is probably an inbreeding effect caused by the action of lethal and semi-lethal genes when brought together in a homozygous state. This explanation could account for the very variable effects of self-pollination on the trees studied. Some viable seed was also obtained from cones isolated and not pollinated. The seedlings are diploid and the possible causes of agamospermy are discussed. A study of the inbred progeny shows that self-pollination usually results in seedlings which are smaller and less vigorous than those from controlled cross-pollination. The seedlings from wind-pollination were intermediate and the small size of some suggests that self-pollination may have occurred. The practical aspects of self-pollination in relation to both the natural and artificial regeneration of forest land are briefly discussed.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".