The characterization of key physiological traits of medicinal cannabis (Cannabis sativa L.) as a tool for precision breeding

Abstract

Background For 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. Results A 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. Conclusions Our 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.

Impact of Three Different Light Spectra on the Yield, Morphology and Growth Trajectory of Three Different Cannabis sativa L. Strains

“…This finding establishes the groundwork for the use of various pruning techniques to shift the branch/stem ratio towards the development of branches, such as topping, in order to realize an increase in total dry yield [ 46 , 47 ]. The results support the hypothesis that taller plants are quicker to harvest [ 48 ], as A4 had the earliest harvest date. However, we cannot confirm the theory of higher productivity of tall plants in terms of yield parameters, as A4 produced the lowest yield.…”

Empirical Evaluation of Inflorescences’ Morphological Attributes for Yield Optimization of Medicinal Cannabis Cultivars

“…A detailed description of the plants’ material used and the cultivation and physiological evaluation methods performed has been previously published ( Naim-Feil et al, 2021 ). The following section will present a summarized version of the above and will expand on inflorescence evaluation techniques and image analysis methodologies.…”

“…The trial was designed in a randomized incomplete block design manner and 4–5 plant replicates of each genotype were examined in order to refine the effect of genetic factors on the phenotypic performance ( Naim-Feil et al, 2021 ).…”

“…Plant harvest was performed selectively when ∼70% of the overall florets’ stigmas turned brown ( Supplementary Figure 1A ). The spatially adjusted genotypic mean of plant height (PH) range on harvest day spans from 95 to 157 cm with an overall mean of 122 cm ( Naim-Feil et al, 2021 ). Harvested plants ( Figure 1 ) were processed under both fresh (on harvest day) and dried (following drying) states.…”

Phenotype correlation analysis and excellent germplasm screening of herb Bletilla Rchb. f. based on comprehensive evaluation from thirty-three geographic populations

“…The correlation is used in the context of a linear relationship between 2 continuous variables and the Pearson correlation coefficient is typically used for jointly normally distributed data [ 25 ]. Correlation analysis can be used to measure the relationship among yield, quality and agronomic traits to determine which trait affects yield and/or quality [ 26 , 27 ].…”