Notice bibliographique
Résumé
Maize is a major cereal crop that requires a well-developed root system to support the production of ≥8 tonnes of grain ha-1 in Quebec, Canada. Maize has pre-embryonic (primary and seminal) and post-embryonic (crown and brace) roots that are usually colonized by arbuscular mycorrhizal fungi. However, root colonization with arbuscular mycorrhizal fungi may be constrained by fertilizer use, particularly when phosphorus (P) fertilizers are applied and the plant-available phosphorus concentration of soil increases, based on greenhouse and growth bench experiments. Furthermore, maize root types may have different amounts of arbuscular mycorrhizal fungi colonization that are not detected with random sampling, which may create a bias in estimating the root colonization percentage. The objectives of this thesis were 1) to determine whether maize root colonization by arbuscular mycorrhizal fungi varied with the plant-available P concentration in soil, based on a gradient of Mehlich-3 extractable P levels following 3 yr of organic and inorganic P fertilizer application to agricultural field plots, 2) to determine if greater root colonization by arbuscular mycorrhizal fungi is associated with more P uptake by maize, and 3) to compare the arbuscular mycorrhizal fungi colonization in maize roots collected at random or from anatomically distinct types (primary, seminal and crown roots) from the V3 to V6 growth stages. The field experiment involved collecting maize plants from agricultural plots with a 3 yr history of organic and inorganic P fertilizer treatments that created a 20-fold difference in the plant-available P concentration, from 12 to 204 mg Mehlich-3-P kg-1. Although the proportion of maize roots colonized with arbuscular mycorrhizal fungi increased from 26 - 2% during vegetative growth (V8 and VT growth stages) to 46 - 2% in the reproductive R2 and R6 stages, root colonization was not affected by P fertilizer application. There was more arbuscular mycorrhizal fungi colonization of maize roots with an increase in plant-available P concentration in soil (r=0.12, P=0.05, n=237), and greater root colonization by arbuscular mycorrhizal fungi was associated with greater P uptake in the maize shoots (r=0.53, P<0.001, n=240). This finding may reflect the greater soil fertility in plots with higher P fertilizer inputs, rather than a direct effect of arbuscular mycorrhizal fungi on P acquisition by maize. In a controlled growth chamber experiment with non-sterile field soil, arbuscular mycorrhizal fungi colonization was evaluated from the V3 to V6 growth stages on distinct maize root types – primary, seminal, and crown – as well as a random sample of lateral roots. Root colonization by arbuscular mycorrhizal fungi increased during maize growth and was always greater in the primary and seminal roots than in the crown and mixed samples. Crown roots were 3–4 times longer with greater surface area, diameter, and volume than primary and seminal roots, but there was no difference in the lignin, cellulose, and hemicellulose content of these root types. Thus, the abundance of arbuscular mycorrhizal fungi on maize roots is affected by root sampling procedures. In summary, this work reveals that arbuscular mycorrhizal fungi are robust colonizers of maize roots, regardless of soil P levels, with preferential colonization of the pre-embryonic primary and seminal roots during early vegetative growth stages
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,000 | 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 ».