The effect of plant density and photoperiod on flowering time, growth and yield of subtropical hemp (Cannabis sativa L.)
Notice bibliographique
Résumé
Industrial hemp (Cannabis sativa L.) production is experiencing a significant increase in worldwide production since regaining popularity in many countries since the 1990's. Currently, production in Australia is very limited, and no major grain or fibre processing facilities yet exist, owing to the lack of suitable low THC (A9-tetrahydrocannibinol) varieties. Hemp production in subtropical regions of Australia is particularly limited as short day lengths (photoperiods) result in early plant maturity, and thus, poor yielding crops. The aim of this research is to determine the viability of a new variety of hemp, bred specifically for subtropical production whilst determining the effects of day length and plant density on yield and flowering time. Trials were conducted in Bundaberg, QLD in 2010-2012 in both field and controlled environment (plastic house) settings. Plant densities of 100, 200, 300 and 400 plants m-2 were compared for fibre production and densities of 50, 80, 100 and 150 plants m2 were compared for grain production to assist in the establishment of appropriate commercial sowing rates. Harvested fibre yields were greatest at 300 plants m2 whereas grain yields were greatest at 150 plants m2, with the potential of even higher yields at densities greater than 150 plants m2. Photoperiod experiments were conducted in a controlled plastic house evaluating plant responses to varying photoperiods. Treatments comparing ambient day length, 13 hour 40 minute fixed photoperiod and 14 hour 40 minute fixed photoperiod determined that a 13 hour 40 minute photoperiod did not significantly prolong vegetative growth compared to natural day lengths in the hemp variety BundyGem but at 14 hours 40 minutes maturity times were significantly delayed, thereby contributing to greater plant height and fibre yield. Previous research also suggests that a critical photoperiod of between 14 and 16 hours is required before flowering is delayed in hemp. This theory was supported by a field experiment whereby successive plantings of BundyGem throughout the spring/summer period of 2011/2012, flowered at the same age despite subtle changes in day length for the growing period (never exceeding 13 hours 40 minutes). This research confirms that subtropical fibre hemp is not yet suitable for subtropical production in Australia with existing varieties due to the limitation of photoperiod on yield. Grain production may still be viable despite early plant maturity with yields comparable with those produced in Europe and Canada.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| 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) | 0,028 | 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 tête enseignante, 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 ».