Exploring the influence of abiotic factors on the hemp field retting process: analyzing the impact of moisture

The industrial applications of hemp fibres, such as construction materials and textiles, require the production of high-quality and uniform fibres, which possess specific mechanical and environmental properties. The retting process is essential in achieving this as it facilitates the mechanical extraction of fibres by breaking down the binding components between fibres and woody parts of the plant. The retting process involves the colonization of the plant stem by microbial communities (bacteria and fungi), which are the primary actors of this process. These communities produce specific enzymes that degrade the plant cell wall material and release the fibres. However, the current practice of field retting is empirical and influenced by various abiotic factors, particularly climatic conditions, which can result in inconsistent fibre properties. Abiotic factors such as moisture level could modulate the microbial diversity of structures and functionalities. This highlights the importance of understanding the impact of these factors on microbial communities dynamics and the resulting fibres properties. In this study, we investigate the impact of moisture on the evolution of hemp (Futura 75 variety) field retting under a Mediterranean climate (Southern France). High-throughput sequencing (HTS) was used to investigate the dynamics of microbial communities during retting. To achieve this goal, the study focuses on analyzing the structure, diversity, and potential enzymatic functions of both bacterial and fungal communities during 6 week of retting period. In addition, the physicochemical and biochemical properties of retted hemp stem and fibres were evaluated. The findings of this study could improve the identification of optimal conditions for enhancing the efficiency of field retting.