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

Abstract

In recent decades with the reacknowledgment of the medicinal properties of Cannabis sativa L. (cannabis) plants, there is an increased demand for high performing cultivars that can deliver quality products for various applications. However, scientific knowledge that can facilitate the generation of advanced cannabis cultivars is scarce. In order to improve cannabis breeding and optimize cultivation techniques, the current study aimed to examine the morphological attributes of cannabis inflorescences using novel image analysis practices. The investigated plant population comprises 478 plants ascribed to 119 genotypes of high−THC or blended THC−CBD ratio that was cultivated under a controlled environment facility. Following harvest, all plants were manually processed and an image of the trimmed and refined inflorescences extracted from each plant was captured. Image analysis was then performed using in-house custom-made software which extracted 8 morphological features (such as size, shape and perimeter) for each of the 127,000 extracted inflorescences. Our findings suggest that environmental factors play an important role in the determination of inflorescences’ morphology. Therefore, further studies that focus on genotype X environment interactions are required in order to generate inflorescences with desired characteristics. An examination of the intra-plant inflorescences weight distribution revealed that processing 75% of the plant’s largest inflorescences will gain 90% of its overall yield weight. Therefore, for the optimization of post-harvest tasks, it is suggested to evaluate if the benefits from extracting and processing the plant’s smaller inflorescences outweigh its operational costs. To advance selection efficacy for breeding purposes, a prediction equation for forecasting the plant’s production biomass through width measurements of specific inflorescences, formed under the current experimental methodology, was generated. Thus, it is anticipated that findings from the current study will contribute to the field of medicinal cannabis by improving targeted breeding programs, advancing crop productivity and enhancing the efficacy of post-harvest procedures.

The Cannabis Plant as a Complex System: Interrelationships between Cannabinoid Compositions, Morphological, Physiological and Phenological Traits

“…These observations support Woods et al (2021) [ 77 ], suggesting that the loci of agronomic and biochemical traits are predominantly independent of each other. Regarding morphological parameters and cannabinoid productivity, our previous prediction equation for IDB showed the efficacy of Inf.W measurements in forecasting inflorescences yield [ 59 ], and building on this data, the current findings uncovered a positive relationship also between Inf.W and TCPP ( Figure 3 ). Moreover, the positive association between TCPP and PH indicates that regardless of the genotypic partitioning based on the main cannabinoid profiles, high-stature plants are more productive ( Figure 3 ).…”

“…Previously, broad inconsistencies were identified across the physiological and phenological traits of the intact plant [ 60 ] as well as across the inflorescence morphological attributes [ 59 ] among genotypes that are vernacularly associated with the same strain groups. The current study extends these findings and demonstrates that this inconsistency applies also to the plant’s cannabinoid profile ( Figure 2 and Figure 4 ).…”

“…This reflects that the traits that generate the predictions differ between the two groups. Previously, we demonstrated that IDB can be predicted solely by measuring the average width of 10 apical inflorescences [ 59 ]. Findings from the current study provide an exciting advancement for the prediction of cannabinoid production, whereby, it is the first model which demonstrates that an array of morphological and phenological parameters can be used for the prediction of TCPP.…”

“…However, given that the cannabis plant is an intricate system combining physiological, phenological, morphological and agronomical attributes, we propose that a holistic understanding of the broader interplay between these factors may improve our understanding of the cannabis plant as a production unit. Previous research has identified associations between physiological, morphological and phenological parameters and inflorescence biomass [ 59 , 60 ]. The current study intends to build on these findings and examine whether these parameters are also associated with cannabinoid production and whether the deconvolution of these complex interplays can improve the prediction models of plant productivity.…”

Cannabis sativa L.: Crop Management and Abiotic Factors That Affect Phytocannabinoid Production

“…Coffman and Gentner (1975) [49] observed that, as plant height increased, the concentration of THC in the leaf tissue generally decreased. However, other floral characteristics besides the inflorescence biomass (such as the number of flowers, length, width, uniformity, perimeter, and distribution) should be explored, as they can influence the final productivity [50].…”