Soilless culture as a novel strategy for maximizing growth performance and fiber yield in industrial hemp (Cannabis sativa L.)

Hemp (Cannabis sativa L.) is one of the oldest cultivated plants in human history. It is a valuable plant that has economic value for all industrial branches. The hemp plant has fibers of the highest quality. Accordingly, research aiming to enhance the fiber yield of hemp has significant agronomic and industrial relevance. To this end, three soilless media treatments were applied to the modified Hoagland solution. The effects of N: P:K/255:45:267 (A1), A1 + 10 mg/L silicon (A2), and A1 + 1 mg/L indole butyric acid (A3) on plant growth and fiber yield were investigated in Narlı hemp (Cannabis sativa L.), a registered local variety (Türkiye), in deep water culture and soil media (A4). The analysis determined that the soilless medium was more productive than the soil medium in terms of root fresh-dry weight, stem fresh-dry weight, stem length, stem thickness, leaf length and width, relative water content (RWC), photosynthetic pigment content, fiber content, and total cellulose content. According to these results, the lowest values were obtained in the soilless medium in terms of malondialdehyde (MDA) and leaf secondary metabolite (cannabidiol: CBD, tetrahydrocannabinol: THC, and cannabinol: CBN) contents, which indicate stress in the plant. CBD was measured %0.0213, %0.0134, %0.0395, %0.0326, THC was measured %0.002, %0.0017, %0.0032, %0.0033, CBN was measured %0.0003, %0.0002, %0.0002, %0.0009 (A1, A2, A3, A4 respectively). Considering all the parameters studied, the hemp plant grown in the deep water culture medium containing Si yielded the best results among the treatments. The fiber content was 29.12% in A2, 24.02% in A1, 19.99% in A4, and 13.74% in A3. The cellulose content was determined to range from 61% to 82% on average in the treatments tested. The highest total cellulose content of 82% was obtained from treatment A2. The current study revealed that silicon (Si) treatment significantly increased fiber and cellulose contents. Incorporating such treatments into production models is regarded as a cost-effective and efficient strategy.