International Journal of Horticulture, 2025, Vol.15, No.4, 171-184 http://hortherbpublisher.com/index.php/ijh 175 Breeding strategies for Cannabis vary depending on the intended use of the plant. For medicinal purposes, breeding programs focus on enhancing the production of specific cannabinoids and terpenes that have therapeutic benefits. For instance, gene copy number variations in cannabinoid synthase genes have been linked to differences in cannabinoid content, providing targets for breeding programs aimed at optimizing medicinal properties (Vergara et al., 2019). In contrast, industrial hemp breeding programs prioritize traits such as fiber quality, biomass production, and resistance to pests and diseases. The development of SSR markers and other genomic tools has facilitated marker-assisted selection, enabling more precise and efficient breeding of Cannabis for both medicinal and industrial applications (Zhang et al., 2020; Borin et al., 2021). 4 Environmental Factors AffectingCannabis Growth and Diversity 4.1 Global distribution of Cannabis species Cannabis species are distributed globally, with both wild and cultivated varieties found in diverse environments. The geographic distribution of Cannabis is influenced by historical cultivation practices, legal regulations, and environmental conditions. For instance, the phenotypic and chemotypic traits of Cannabis can vary significantly based on the region of cultivation, as seen in the comprehensive phenotypic characterization of diverse drug-type Cannabisvarieties from the Canadian legal market (Lapierre et al., 2023). This study highlights the significant variation in agronomic, morphological, and cannabinoid profiles within a population, which is influenced by the geographic origin and cultivation practices. 4.2 Impact of soil, light, and water The growth and diversity of Cannabisare significantly affected by soil types, lighting conditions, and watering regimes. Different soil types can influence the physiological and metabolic responses of Cannabis plants. For example, industrial hemp grown on abandoned mine land soil showed high tolerance to heavy metals and increased cannabidiol content compared to plants grown in commercial soils (Husain et al., 2019). This indicates that soil composition can affect both growth and secondary metabolite production. Lighting conditions, including light intensity and spectrum, play a crucial role in Cannabis growth and cannabinoid production. A meta-analysis identified light intensity, quality, and photoperiod as critical factors influencing Cannabisyield and THC accumulation (Backer et al., 2019). Additionally, different light spectra can manipulate secondary metabolism, affecting CBD, CBDA, and terpene concentrations (Reichel et al., 2022). For instance, specific light spectra were found to significantly influence the concentrations of these compounds, demonstrating the potential for optimizing light conditions to enhance desired plant characteristics. Water availability also impacts Cannabisgrowth and essential oil production. A study conducted in Lebanon revealed that optimal irrigation (Iopt) significantly increased biomass, dry matter, and plant height compared to reduced irrigation (I50) (Sleiman et al., 2022). However, the essential oil content was not statistically affected by the irrigation regime, suggesting that water stress may not always influence secondary metabolite production. 4.3 Climate and geographic distribution Climate plays a pivotal role in shaping the phenotypic traits and chemotype of Cannabis. Environmental factors such as temperature, altitude, and CO2 concentration are directly related to the yield and stability of phytocannabinoids (Trancoso et al., 2022). For instance, variations in temperature and altitude can influence the growth cycle and cannabinoid profiles of Cannabis plants, leading to differences in phenotypic traits. The geographic distribution of wild and cultivated Cannabis varieties is also influenced by climate. Wild Cannabis varieties are often found in regions with specific climatic conditions that favor their growth, while cultivated varieties are distributed based on agricultural practices and legal frameworks. The study on the environmental impacts of Cannabis cultivation highlights that both indoor and outdoor growing conditions can have significant environmental implications, including water usage, energy consumption, and soil erosion (Zheng et al., 2021). These factors must be considered when evaluating the geographic distribution and sustainability of Cannabis cultivation.
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