TY  - THES
T1  - The bioeconomy potential of hemp (Cannabis sativa L.) : challenges of new genotypes and cultivation systems to meet the rising demand for phytocannabinoids
A1  - Burgel,Lisa
Y1  - 2021/08/02
N2  - Cannabis sativa L. as a prime example of a multifunctional crop is excellently suited for recycling management due to its versatility and the usability of the whole plant. Cannabis currently experiences a boom due to its rich phytochemical repertoire, its fibres and valuable oil required in numerous products, and its unique agricultural properties. The medical benefits of C. sativa, based on the phytocannabinoids available in flowers and leaves, are the main focus of attention worldwide. Innovative markets in the food, cosmetics and pharma industry are growing fast, with a focus on cannabidiol (CBD), which is the leading cannabinoid of the cannabis plant. Basically, it is important to differentiate between industrial hemp genotypes and phytocannabinoid-rich (PCR) cannabis genotypes. Industrial hemp meet the 0.2% THC limit mandated by the EU legislation, and therefore, can be legally cultivated by farmers on a field scale. PCR genotypes contain high amounts of non-psychoactive cannabinoids such as CBD and cannabigerol (CBG) in the range of 10 – 30% while their THC content is also below 0.2%. These genotypes are currently being bred but are still barely available on the market. Cannabinoid extraction from industrial hemp cultivated on a field scale could provide a decisive advantage as the harvested biomass quantities could be significantly increased through better land use and cost management, compared to an indoor system. The multi-functionality of the industrial hemp can provide added economic value. Therefore, existing cultivation systems for fibre and oilseed production have to be modified as the harvesting time and harvested organ are expected to differ greatly from those of the present systems. In order to achieve this, publication I dealt with the objective, to determine the yield potential of different EU-registered hemp genotypes with regard to inflorescence and biomass yield as well as cannabinoid content, depending on genotype, growth stage and biomass fraction in an outdoor cultivation system. The cultivation of seven industrial hemp genotypes (Finola, Fédora17, Ferimon, Félina32, Futura75, USO 31 and Santhica27) was carried out in a two-year field experiment. Sampling of leaves and inflorescence, took place at four specific growth stages: vegetative leaf stage, bud stage, full-flowering stage, and seed maturity stage. Dry matter was recorded, and cannabinoids were analysed. The results indicated that the content of cannabinoids highly depended on the genotype and the growth stage. Thus, biomass and inflorescence yields must be considered for an optimized harvest result. Genotype Santhica27 indicated the highest contents of CBG/A. Further, it was found that genotypes such as Futura75, Fédora17, Félina32, Ferimon, Finola and Santhica27, which were highlighted to have a higher CBD/A or CBG/A content compared to other evaluated genotypes, reached the highest yields of threshing residues after seed maturity, and thus a higher CBD/A and CBG/A yield per area. In conclusion, harvesting after seed maturity seems to be economically beneficial. These findings make selected industrial hemp genotypes excellent candidates for multipurpose cropping.
Additionally, the thesis aimed at further standardization of PCR genotypes in indoor cultivation systems. Due to the prescribed requirement of high-quality medical cannabis material, indoor cultivation is in focus as under the system all production parameters can be standardized. The production of cannabinoids under indoor conditions is expensive due to processing costs and regulatory limitations, thus there is an increasing interest in using the available space requirements efficiently. Publication II evaluated the adaptation of the plant architecture, through the targeted use of synthetic phytohormones, aiming for a small and compact plant morphology for various indoor systems. The objective was, to test the impact of exogenously applied plant growth regulators (PGRs), such as NAA, BAP and a mixture (NAA/BAP-mix) of both on the plant architecture of different PCR genotypes. Therefore, genotypes were treated with synthetic phytohormones in various concentrations in a greenhouse experiment. Furthermore, the differences in leaf and flower yields resulting from morphological changes in these genotypes and their CBD/A content was investigated. A genotype-specific impact of applied PGRs on the plant architecture was determined. NAA led to more compact plants with a consistently high floral yield for genotype KANADA, whereas CBD/A content was not affected. Genotypes 0.2x and FED showed reduced floral yields due to the PGRs applications. Publication III dealt with the evaluation of the growth performance of PCR genotypes grown in different substrate compositions substituted with peat alternatives in an indoor cultivation system. The impacts of the following substrate compositions: peat-mix growth media (PM); peat-mix substituted with 30% of green fibres (G30) consisting of coniferous wood and wood chips from pine and spruce wood growth media, and coco coir fibres (CC), on growth performance, biomass and flower yields, biomass nitrogen (N) content as well as CBD/A contents were tested. The results showed that the different substrates had significant impacts on the growth, biomass and floral yields, root development and N tissue content of the tested genotypes. A genotype-specific reaction on floral yield was investigated. While genotype KANADA had the highest floral yields when grown in PM, 0.2x showed no significant differences, with higher floral yields grown in G30 and CC. For both genotypes, no limiting effect on CBD/A content was enacted. It can be concluded, that organic peat alternatives such as green fibres, partly replacing peat in standard growing media, offers a genotype-specific option.
KW  - Hanf
KW  - Anbautechnik
KW  - Anbausysteme
KW  - Phytocannabinoide
KW  - CBD
CY  - Hohenheim
PB  - Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim
AD  - Garbenstr. 15, 70593 Stuttgart
UR  - http://opus.uni-hohenheim.de/volltexte/2021/1917
ER  -