Assessing the Critical Factors Affecting the Winter Survival of Late-Fall-Seeded Selected Spring Crop Species
Notice bibliographique
Résumé
Late fall seeding, defined as sowing prior to soil freeze-up, offers several agronomic advantages over conventional spring planting, including accelerated crop development, enhanced yield potential and reduced exposure to abiotic stresses, such as frost, heat and drought in the following growing season. However, its adoption remains restricted due to inconsistent seedling establishment following overwintering. Lack of freezing tolerance is considered as the main limiting factor to consistent overwintering. This study investigated the physiological, morphological, anatomical, and biochemical mechanisms underlying seed freezing tolerance in key spring crop species of the Canadian Prairies: lines/cultivars of lentil (Lens culinaris Medik.), field pea (Pisum sativum L.), canola (Brassica napus L.), carinata mustard (Brassica carinata A. Braun), brown mustard (Brassica juncea L.), yellow mustard (Sinapis alba L.), wheat (Triticum aestivum L.) and coriander (Coriandrum sativum L.). In chapter 3, five experiments were conducted under controlled and semi-controlled conditions. In experiment 1, seeds from each crop species and lines/cultivars were evaluated for water uptake at two temperatures (+2°C and +23°C), in water and soil media. Then, cultivars with contrasting water uptake profiles were identified and subjected to freezing tolerance assessments in experiment 2, where lethal freezing temperature (LT50) and duration (LD50) were determined for both imbibed and non-imbibed seeds. Oilseed crops and coriander had greater freezing tolerance than pulse and cereal crops, and non-imbibed seeds consistently survived better than imbibed ones. Building on these findings, experiment 3 assessed seedling emergence under simulated fall and spring seeding conditions. Furthermore, experiments 4 and 5 evaluated the same cultivars under natural field conditions, monitoring emergence and establishment following overwintering stress. While laboratory results suggested a clear association between water uptake and freezing tolerance, this correlation was inconsistent in the field. Short-term exposure under thick, consistent snow layers enhanced survival, whereas prolonged exposure disrupted biochemical processes, leading to seed death. In chapter 4, using lentil as a model system, seed traits, such as size, seed coat polyphenol content and protein and amylose levels were associated with reduced water uptake and improved freezing tolerance. In chapter 5, priming with abscisic acid (ABA), a naturally occurring plant hormone, delayed germination and preserved viability short-term, but did not enhance long-term survival. Overall, winter survival of late-fall-seeded spring crops is governed by a complex interplay of seed-specific traits and environmental conditions. Using lentils as a model system, water uptake emerged as the primary factor influencing freezing tolerance, regulated by seed size (thousand-seed weight), seed coat thickness, phenolic acids in the seed coat, and total starch and protein content. Among environmental factors, soil temperature during sowing, snow depth during winter and the number of freeze-thaw-refreeze cycles are critical for seed survival in the field. These findings provide a foundation for breeding and management strategies aiming at improved winter survivability of late-fall-seeded spring crops, with the potential to transform cropping systems across the Canadian Prairies.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
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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 | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 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) | 0,000 | 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 ».