Optimization of hemp production technology for fiber and seed

Abstract

Industrial hemp (Cannabis sativa L.) is one of the most intriguing agricultural crops worlwide. The hypothesis of this work was that industrial hemp properties would be affected by cultivar, seeding date, and row spacing effects on fiber and seed yield as measures of optimal production technology for specific hemp production outcomes. Field experiments were conducted in Bački Petrovac, Serbia (45.3568° N, 19.6173° E, at 82 m) during the 2020 and 2021 seasons following a multi-year pilot study. The study included 5 cultivars (Helena, J x USO31, Bob-1, H x USO31, and Marina). The three seeding dates were at the beginnings of April, May, and June, respectively. The three inter-row spacings were 12.5, 25, and 50 cm (4.92, 9.84, and 19.68 in., respectively). The results indicate that the tallest plants were obtained from plots seeded at 12.5 cm. Plants sown at a spacing of 50 cm exhibited a significant increase in stem thickness compared to those planted with a spacing of 12.5 cm. Overall, the fiber content varied between 26 % and 49.7 %. Cultivar Marina had the highest hemp fiber content (HFC) of all cultivars. The highest seed yield was obtained from cvs. H x USO31 and J x USO31, while cv. Marina had the lowest seed yield. Hemp seeds contained on average 88.6 % unsaturated fatty acids and 66.78 % new polyunsaturated fatty acids. Major polyunsaturated fatty acids in hemp oil were linoleic (C18:2 n6), gamma-linoleic (C18: n6) and linolenic (C18:3 n3) acids of which linoleic acid was most abundant, and it ranged from 45.3 % to 54.8 % in the analyzed seeds. The major monounsaturated fatty acid in the hemp seed oil analyzed in this study was oleic acid (an average of 15.09 % for all cultivars, seeding dates, and row spacing combinations). While the findings from this study are immediately applicable to the traditional hemp-production region of Vojvodina in Serbia, they can also be readily utilized by hemp fiber and seed growers at the same latitude across the world who want to improve agronomic sustainability of hemp, as well as for scientific readers all over the world.