THE INFLUENCE OF POTASSIUM ON CONTENT OF TOTAL POLYPHENOLS AND ANTIOXIDANT ACTIVITY OF ONION (ALLIUM CEPA L.)

Potassium (K) is an essential plant nutrient which is influencing on plant metabolism, plant growth, development of the crops quality and crop yield. The present study was aimed to evaluate the influence of the potassium on the content of the total polyphenols and antioxidant activity on the onion (Allium cepa L.) variety Mundo. The content of the total polyphenols was determined by using the Folin-Ciocalteu reagent (FCR) according to Lachman et al. (2003), who was found that the content of polyphenols in his study were (273.51 +/- 21.00 to 722.15 +/- 30.01 mg.kg(-1)). At the end of the study we concluded statistically that the addition potassium in soil had a positive effect between the content of the potassium in the soil and the content of the total polyphenols on the onion, which was led an increase total polyphenols (P-value= 2.17.10(-3)). On the other hand we found that an the addition the potassium in the soil had negative between the potassium content and values of antioxidant activity on the free radical (DPPH) for onion plant.