A comparative study of seed yield and oil composition of four cultivars of Hemp (Cannabis sativa L.) grown from three regions in northern Iran

Abstract

Cannabis sativa L, commonly known as Hemp, shows numerous health and economic benefits with commercial applications such as in seed production, fiber, oil, and pharmaceutical uses. Hemp oil has been widely acknowledged to have a panoply of health benefits, such as cholesterol lowering properties and decreasing high blood pressure, owing to the presence of two essential fatty acids (linoleic acid and α-linolenic). Given the economic and industrial importance of hemp, the present study was designed in an endeavor to select and compare the best cultivar and region to increase both quantity and quality of hemp oil from Iran. Seeds of two native populations from Iran (Fars and Yazd provinces) and one foreign variety from France (Fedora17, as an industrial hemp cultivar) with its progenies (Fedora17-2) were cultivated in research fields of three locations (Gilan, Golestan, and Alborz province) in Iran. The mature seeds of cultivated plants were collected and their oils were extracted by Soxhlet apparatus and analyzed by Gas Chromatograph. The seed yield was 288.70 to 3182.60 kg ha-1 and oil yield were 0.08 to 0.95 t ha-1 in the studied sites. Also, the range of 1000- seed weight was 5.20 to 15.28 g. The oil content of different varieties varied from 15.46 to 36.63%. Based on the results, the highest seed yield, 1000-seed weight, and oil yield belonged to native populations. It was also determined that Alborz was significantly higher in terms of oil production, 1000-seed weight, and seed and oil yield per hectare compared with the other two regions. The most abundant fatty acid in the samples was linoleic acid, (56.80 to 63.98%), and almost identical in all cultivars and areas studied. The range of linoleic acid and α-linolenic in three regions were 57.55 to 63.98% and 7.57 to 22.91%, respectively. In addition, the palmitic acid content of foreign varieties was higher than that of the native populations in all three locations. Since the interfaces in the production and synthesis of fatty acids in plants are influenced by variation in temperature, light and moisture amount and farming conditions so the percentage and kind of fatty acids in hemp oil can be varied in different regions.