Abstract
BackgroundFor millennia, drug-type cannabis strains were extensively used for various medicinal, ritual, and inebriant applications. However, cannabis prohibition during the last century led to cultivation and breeding activities being conducted under clandestine conditions, while scientific development of the crop ceased. Recently, the potential of medicinal cannabis has been reacknowledged and the now expanding industry requires optimal and scientifically characterized varieties. However, scientific knowledge that can propel this advancement is sorely lacking. To address this issue, the current study aims to provide a better understanding of key physiological and phenological traits that can facilitate the breeding of advanced cultivars.ResultsA diverse population of 121 genotypes of high-THC or balanced THC-CBD ratio was cultivated under a controlled environment facility and 13 plant parameters were measured. No physiological association across genotypes attributed to the same vernacular classification was observed. Floral bud dry weight was found to be positively associated with plant height and stem diameter but not with days to maturation. Furthermore, the heritability of both plant height and days to maturation was relatively high, but for plant height it decreased during the vegetative growth phase. To advance breeding efficacy, a prediction equation for forecasting floral bud dry weight was generated, driven by parameters that can be detected during the vegetative growth phase solely.ConclusionsOur findings suggest that selection for taller and fast-growing genotypes is likely to lead to an increase in floral bud productivity. It was also found that the final plant height and stem diameter are determined by 5 independent factors that can be used to maximize productivity through cultivation adjustments. The proposed prediction equation can facilitate the selection of prolific genotypes without the completion of a full cultivation cycle. Future studies that will associate genome-wide variation with plants morphological traits and cannabinoid profile will enable precise and accelerated breeding through genomic selection approaches.
Highlights
Drug-type cannabis strains were extensively used for various medicinal, ritual, and inebriant applications
Cannabis was adapted to address a varied range of desirable products under diverse environments that lead to a selection of several morphotypes and many genotypes originating from its monotypic genus [6,7,8]
As all of the strains under evaluation originated from legal medicinal cannabis companies, the findings of the current study indicate that despite the significant recreational breeding for high THC plants that took place in recent decades [33,34,35, 38] and a reduction in the genetic diversity of modern strain’s cannabinoid profile [28, 55], a vast phenotypic diversity across physiological and phenological traits still remains (Fig. 1)
Summary
Drug-type cannabis strains were extensively used for various medicinal, ritual, and inebriant applications. Its scientific development ceased and its cultivation and breeding initiatives were required to be conducted in a clandestine manner [2, 24,25,26] These breeding attempts necessitated physiological adaptations [2] and created vigorous varieties which were prosperous under indoor environment conditions [5, 16]. In addition to these adjustments, the cannabis industry was dominated by recreational consumers and breeders were required to consistently enhance the plant’s psychoactive cannabinoid- Δ9-tetrahydrocannabinol (THC) [27,28,29]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
