Characteristics of black medic (Medicago lupulina L.) seed dormancy loss in Western Canada
Notice bibliographique
Résumé
Cover crops are an important innovation in sustainable cropping systems. The successful use and management of black medic (Medicago lupulina L.) as a self-regenerating cover crop requires a better understanding of its physical seed dormancy. In order to break this seed dormancy, it appears that a low temperature 2-stage seed softening process is required. However, whether or not this 2-stage process is required for black medic seed softening in Western Canada is unclear. Also, the influence of the presence of a companion crop, medic population type, seed burial depth and seed production environment on black medic production and seed softening is unknown. Field and controlled environment studies were established in 2003 and 20O4 in an effort to address these questions. The results from a field study conducted in different prairie environments showed that although, seed production environment, the presence of a companion crop, and medic population affected the growth and development of the black medic plants, they did not affect initial seed dormancy. A second field study tested the effect of seed production environment, seed burial depth and population on seed softening. Results indicated that there was an effect of population on summer seed softening, which suggested that there were differences in seed dormancy between a population of black medic that had been subjected to selection pressures (e.g., herbicides, competition) for 12 years versus one that had not (Foundation stock). Therefore, this suggests that some genetic drift had occurred within the population. The results also indicated that there was an effect of seed burial depth on seed softening, with more seed softening occurring for the buried seed during winter/spring and more for the surface seed during summer, and these differences appeared to be somewhat linked to differences in soil temperature. Results of this field study suggested that black medic in Western Canada goes through a 2-stage softening process. Hence, a controlled environment study was established to test this hypothesis. Results from both studies confirmed that a 2-stage softening process is required for black medic softening in western Canada. Stage 1 requirements appear to be met by exposing seed to temperatrues between-5oC and 5oC for at least 4 weeks, while exposure of the seed to a low fluctuating temperature (e.g. 15/6oC) for a short period of time (i.e., approximately 4 days) appears to meet stage 2 requirements. In summary, this research has provided us with valuable information about black medic seed softening under Western Canadian conditions, which will hopefully lead to a better understanding of how to best manage and utilize black medic as a self-regenerating cover crop in a Western Canadian cropping system.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».