Foliar Symptomology, Nutrient Content, Yield, and Secondary Metabolite Variability of Cannabis Grown Hydroponically with Different Single-Element Nutrient Deficiencies

Abstract

In controlled environment production systems, Cannabis sativa (hereafter cannabis) is a commodity with high nutrient demands due to prolific growth under optimized environmental conditions. Since nutrient deficiencies can reduce yield and quality, cultivators need tools to rapidly detect and evaluate deficiency symptoms so corrective actions can be taken quickly to minimize losses. We grew cannabis plants in solution culture with different individual nutrient elements withheld from the solutions to identify deficiency symptoms. Control plants received a complete nutrient recipe, whereas the following single elements were withheld from the respective nutrient deficiency treatments: N, P, K, Ca, Mg, S, Fe, and Mn. The nutrient treatments began when the photoperiod was switched to a 12/12 h (light/dark), and plants were grown to commercial maturity. Plants were monitored daily, and the development of visual deficiency symptoms were recorded. Photographs of each plant were taken weekly. Upon the onset of visual deficiency symptoms, both upper- and lower-canopy foliage were analyzed for nutrient element concentrations. At harvest, plants were evaluated for biomass partitioning, and the cannabinoid composition of inflorescence tissues. This manuscript describes the onset and progression of nutrient deficiency symptoms (with pictures), relates symptomology to foliar nutrient analyses, and contextualizes the relationships between nutrient deficiencies and cannabis growth, yield, and quality. Aboveground vegetative fresh weights were reduced by 73% in the -N treatment and 59% in the -P treatment, compared with the control. All deficiency treatments except for -Fe and -Mn had floral yields reduced by between 33% to 72%, compared with the control. Overall, deficiencies of individual nutrients can substantially reduce vegetative growth and inflorescence yield, although only minor effects were observed in secondary metabolite composition. The onset of individual deficiency symptoms did not always correspond with elemental analysis of foliar tissues. Cultivators should take an integrated approach in diagnosing nutrient deficiencies and take timely corrective actions to optimize productivity and minimize losses to yield and quality.

Environmental Impact of Outdoor Cannabis Production

“…This could be the first report of a fertilizer treatment affecting cannabinoid content at this magnitude (∼30% increase). This was caused by N deficiency, as evidenced by leaf N content being between 1.5 and 2.5% as opposed to 2.2 and 4.3% in plants with sufficient N. , This has been observed with tobacco plants (Nicotiana tabacum) and hops (Humulus lupulus), where phenolic and alkaloid secondary metabolites content increase under N deficiency. , This LCA is the first to explore the potential benefits of this compound for cannabis.…”

Effect of augmented nutrient composition and fertigation system on biomass yield and cannabinoid content of medicinal cannabis (Cannabis sativa L.) cultivation

“…Undoubtedly, nutrition plays a pivotal role in shaping the development, functionality, and metabolic processes of various plant organs and tissues ( Shiponi and Bernstein, 2021b ; De Prato et al., 2022 ). Existing knowledge has extensively documented the ideal thresholds of specific macronutrients, including N, P and K, along with micronutrients like Fe, necessary for ensuring the normal growth and functioning of both root systems and above-ground biomass ( Shiponi and Bernstein, 2021a ; Shiponi and Bernstein, 2021b ; Malík et al., 2022 ; Saloner and Bernstein, 2022 ; Llewellyn et al., 2023 ), as well as the production of valuable secondary metabolites in medicinal cannabis plants ( Caplan et al., 2017 ; Bernstein et al., 2019b ; Shiponi and Bernstein, 2021b ; Saloner and Bernstein, 2022 ). It is crucial to emphasize that nutrient solution fertigation was provided to the plants only up to the ninth week of cultivation.…”

“…Phosphorus, for instance, influences root growth, flower and seed production, and stem strength ( Zheng, 2022 ) and affects terpene profiles in aromatic plants ( Rioba et al., 2015 ). While inadequate P supplementation can lead to deficiency symptoms, excessive supply often accumulates in roots ( Shiponi and Bernstein, 2021a ; Llewellyn et al., 2023 ). The impact of increased phosphorus supplementation on medicinal cannabis varies across organs and compounds, with key cannabinoids remaining unaffected in upper flowers ( Bernstein et al., 2019b ; Shiponi and Bernstein, 2021b ).…”

“…Iron facilitates oxidation-reduction and electron transfer reactions, activates enzymes, and is essential for photosynthesis and respiration ( Briat et al., 2015 ; Zheng, 2022 ). Fe deficiency leads to chlorosis in young leaves, impaired root development, yield reduction, and compromised nutritional quality in crops ( Kumar et al., 2021 ; Llewellyn et al., 2023 ). Fe concentrations in plant nutrition may have varying effects on secondary metabolite production ( Shi et al., 2018 ; Chaouqi et al., 2023 ), but no specific study has explored the influence of Fe nutrition in indoor medicinal cannabis cultivation.…”