BIOFORTIFICATION OF SPINACH PLANTS APPLYING SELENIUM IN THE NUTRIENT SOLUTION OF FLOATING SYSTEM

Selenium (Se) is a very important element for human health. It is involved in defense mechanisms and biosynthesis of hormones in adult and babies. The Se is a trace element and in the human body is involved in the membrane pro-tection and has anti-cancer action. The Se is a cofactor of glutathione peroxi-dase and may play an important role against oxidative tissue damage. The aim of this work was to evaluate the floating system for enriching the baby leaf plants by applying the Se directly in the nutrient solution. This experiment was performed using spinach (Spinacia oleracea L.) plants grown in the nutrient solution containing 0, 2.6, 3.9 and 5.2 ?M Se applied as Na2SeO4. At harvest time the yield, Se content and quality parameters such as ni-trate, reducing sugars and sucrose were determined. The yield was not affected by treatments and depended by seasons. The Se content in leaves linearly increased with Se concentration in the nutrient solution. The highest value was 160 mg·kg-1 DW. Spinach leaves in the 2.6 and 3.9 ?M accumulated 9-11 ?g·g-1 DW and were the adequate concentra-tions for providing the recommended dietary allowance of 55 ?g·d-1 for adults. Reducing sugars expressed as glucose equivalent did not change among treat-ments and ranged from 6 to 9 mg·g-1 FW. The sucrose content ranged from 0.6 to 3 mg·g-1 FW but no differences were observed among treatments. Nitrate contents in leaves were not affected from Se treatments and ranged from 3898 to 4475 mg·kg-1 FW.