The study aims to determine the nutritional value of hemp seed expressed by the oil content and by the concentration of metals (Ca, Mg, K, Fe, Mn, Zn and Cd), for five varieties of monoecious and dioecious hemp seeds approved in Romania, comparative with the concentration of these metals in the soil.
The content of oil in hempseed registers a slight decrease in the production records of 2011, losses due to drought and low levels of precipitation during the growth period. The greatest loss is found in Diana monoecious variety (26.54-20.82%) followed by Zenit varieties (27.37-22.97%), Armanca (29.27-25.32%), Silvana (28.89-25.04%) and Denise (26.96-25.30%). Siccative hemp oil has a yellowish green color and an iodine index of 140–156 g I2/100 g oil. Hemp seed are rich in mineral based Ca (144–955 mg/100 g seed), Mg (237–694 mg/100 g seed), K (463–2821 mg/100 g seed), Fe (1133-2400 mg.kg-1), Mn (63–110 mg.kg-1) and Zn (42-94 mg.kg-1). For the soil the following macroelements concentrations were determined: Ca (2100–2520 mg.kg-1), Mg (320–376 mg.kg-1) and K (232–257 mg.kg-1). Mn (156–197 mg.kg-1) and Zn (54–67 mg.kg-1) remain within normal limits for Romania. The soils in the experience area contain large amounts of Fe (19000–20430 mg.kg-1). The presence of K in large quantities determines the accumulation of large quantities of Fe in the soil.
Hempseed belonging to the five Romanian varieties are rich source of nutrients (Ca, Mg, K) and unsaturated oil easily digestible by the body, but the presence of Cd concentrations above the upper limit puts a question mark over the use of seeds in various food products. Hemp extracts easily certain metals from the soil. Significant amounts of Fe (1133–2400 mg.kg-1), Mn (63–110 mg.kg-1), Zn (42–94 mg.kg-1) and Cd (1.3-4.0 mg.kg-1) are found in hemp seeds. Hemp (Cannabis sativa L.) is included among plants suitable for phytoremediation of soil contaminated with cadmium, zinc and iron.