Semester of Graduation

Fall 2024

Degree

Master of Science (MS)

Department

School of Plant Environmental and Soil Sciences

Document Type

Thesis

Abstract

The macro and micronutrient contents and bioactive compounds in young immature and fully expanded young leaves of two different hemp (Cannabis sativa) chemotypes [cannabidiol (CBD)-type and fiber-type) were quantified. The effects of leaf physiological developmental stage and harvest time on total phenolic content, individual phenolic acids, antioxidant activity, vitamin C concentration, nutrient content, cannabinoids and organic acids were determined. Both hemp chemotypes differed in their bioactive compound and nutrient composition at both developmental stages and harvest times [30 and 60 days after transplanting (DAT)]. Immature leaves of the CBD-type hemp harvested at 60 DAT had the highest total phenolic content. The principal individual phenolic acids found in both the chemotypes were gallic acid, rutin, and ferulic acid. Young immature leaves of the fiber-type hemp harvested at 30 DAT had the highest antioxidant activity.

The young immature leaves of the CBD-type hemp harvested at 60 DAT had the highest total vitamin C concentration. The immature leaves of both chemotypes had a higher total phenolic content, antioxidant activity, and vitamin C concentration compared to the recent fully expanded leaves at both harvesting times. Nitrogen and potassium were the predominant macronutrients found in both the chemotypes at 60 DAT. Iron was the major micronutrient found in CBD-type hemp leaves, whereas manganese was the abundant micronutrient found in fiber-type hemp leaves. The major organic acid found in CBD-type leaves was succinic acid, whereas in fiber-type leaves were quinic acid and l-malic acid. Cannabidiolic acid (CBDA) was the principal cannabinoid quantified in both the chemotypes and leaf developmental stages. Terpenoids were the major class of volatile organic compounds quantified and young immature leaves had the higher concentrations.

In an additional study, two hemp chemotypes (CBD-type and fiber-type) were grown under artificial lighting for 30 days. Light intensity and photoperiod were the two light parameters tested. Total phenolic content, antioxidant activity, individual phenolic acids, total vitamin C concentration, ascorbic acid content, organic acids and cannabinoids were analysed in hemp leaves harvested 30 DAT.

Date

10-28-2024

Committee Chair

Picha, David

Available for download on Thursday, October 28, 2027

Included in

Horticulture Commons

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