The Shape of Cannabis sativa L. Seeds for the Differentiation of Commercial Medicinal Cultivars from Argentina.

Abstract

The Cannabis sativa L. plant has been used since ancient times as food, a source of fiber, and medicine, resulting in crosses that led to hybridization that currently does not allow for morphological differentiation among the three varieties of the genus (sativa, indica, and ruderalis). Currently, three chemotypes are differentiated based on their cannabinoid content (THC/CBD). Starting in the year 2023, seeds of two contrasting chemotype medicinal cultivars developed by CONICET (National Council for Scientific and Technical Research) and registered with INASE (National Institute of Seeds) can be commercialized in Argentina. In a previous study, we reported a relationship between the shape of Cannabis seeds and the chemical fingerprint associated with the chemotype. The objective of this study is to morphometrically characterize the seeds of two cultivars of Cannabis sativa L. with contrasting chemotypes: type I (high THC) and type III (high CBD). For this purpose, 2D geometric morphometrics based on landmarks and semilandmarks were used, allowing for the independent study of shape and size variation. Seed size between cultivars was compared using univariate statistics of an unbiased size estimator. To understand the magnitude and direction of shape change and determine shape characters that maximize separation between cultivars, a multivariate statistical approach was employed. Seeds belonging to the Malvina cultivar (type I cultivar, THC only) had, on average, smaller size and a rounded shape, whereas seeds from the Pachamama cultivar (type III, high CBD content) had larger size and a tendency towards an elongated oval shape. The use of a discriminant function based on seed shape allowed for over 97% correct assignments between cultivars. Our results could be used for implementing seed shape as a quality and authenticity seal for registered cultivars in the Argentine Cannabis market.