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Hemp (Cannabis sativa L.) is a bast-fiber crop well-known for the great potential to produce sustainable fibers. Nevertheless, hemp fiber quality is a complex trait, and little is known about the phenotypic variability and heritability of fiber quality traits in hemp. The aim of this study is to gain insights into the variability in fiber quality within the hemp germplasm and to estimate the genetic components, environmental components, and genotype-by-environment (G×E) interactions on fiber quality traits in hemp. To investigate these parameters, a panel of 123 hemp accessions was phenotyped for 28 traits relevant to fiber quality at three locations in Europe, corresponding to climates of northern, central, and southern Europe. In general, hemp cultivated in northern latitudes showed a larger plant vigor while earlier flowering was characteristic of plants cultivated in southern latitudes. Extensive variability between accessions was observed for all traits. Most cell wall components (contents of monosaccharides derived from cellulose and hemicellulose; and lignin content), bast fiber content, and flowering traits revealed large genetic components with low G×E interactions and high broad-sense heritability values, making these traits suitable to maximize the genetic gains of fiber quality. In contrast, contents of pectin-related monosaccharides, most agronomic traits, and several fiber traits (fineness and decortication efficiency) showed low genetic components with large G×E interactions affecting the rankings across locations. These results suggest that pectin, agronomic traits, and fiber traits are unsuitable targets in breeding programs of hemp, as their large G×E interactions might lead to unexpected phenotypes in untested locations. Furthermore, all environmental effects on the 28 traits were statistically significant, suggesting a strong adaptive behavior of fiber quality in hemp to specific environments. The high variability in fiber quality observed in the hemp panel, the broad range in heritability, and adaptability among all traits prescribe positive prospects for the development of new hemp cultivars of excellent fiber quality.

International audience

Pour la determination quantitative du delta-9-tetrahydrocannabinol (Δ-9-THC) des varietes de chanvre, une methode communautaire a ete publiee [1]. Bien que cette methode permette de controler efficacement les varietes cultivees [2], nous avons eu l’occasion de commenter plusieurs points de cette methode, notamment ceux ayant trait au prelevement au champ qui peuvent influer fortement sur le resultat [3] et nous avons propose une simplification en prenant en compte la valeur du rapportα = Δ-9-THC/CBD [4]. Nous souhaitons maintenant revenir sur les consequences des etapes comprises entre le prelevement au champ et l’analyse et mesurer leur impact sur les teneurs en cannabinoides.

Le chanvre industriel est cultive sur des surfaces limitees (surfaces proches de 11 000 ha en France en 2014, source CETIOM), mais comme pour toute espece cultivee, une activite de selection est necessaire. Celle-ci est conduite en France par un acteur unique depuis plusieurs dizaines d’annees, la Federation Nationale des Producteurs de Chanvre (FNPC). Cet article presente les differents criteres de selection actuels et a venir. Certains axes historiques sont toujours travailles aujourd’hui, comme la teneur en Δ9-tetrahydrocannabinol, dans un souci de respect des reglementations, ou le maintien de l’etat monoique, permettant une culture mecanisee. D’autres criteres de selection ont evolue, en particulier la precocite varietale et le rendement paille. Pour ces deux criteres, de nouveaux objectifs sont apparus : pour la precocite varietale, l’equipe de selection cherche a elargir la gamme existante, quant au rendement paille, le but actuel est d’ameliorer la productivite de la plante, c’est-a-dire d’augmenter le rendement a precocite constante. Enfin, de nouveaux axes de selection apparaissent, comme par exemple la facilite de defibrage et la tolerance a l’orobanche.