TOTAL PHENOLIC, ANTHOCYANINS AND TBA-ACTIVE PRODUCTS IN BUCKWHEAT PLANTS UNDER NaCl IMPACT

Abstract

High salt concentration in soils cause osmotic and ionic stress for plants, along with oxidative stress and inhibition of growth and development, as a consequence, reducing the yield of many crops important for agriculture. Buckwheat (Fagopyrum esculentum Moench.) is classified as a salt-sensitive glycophyte plant, but salt tolerance of this culture is higher among many important food crops. The salt impact on the total levels of phenolics, anthocyanins and TBA-active products as the oxidative lipid peroxidation parameter, was determined in buckwheat plants (cv. Ukrainka) on 48, 72 h and 7^th days of high NaCl exposure. Plants were grown on the Ѕ Hoagland–Arnon’s nutrient solution with/without addition of 100 mM NaCl. After 72 h of salt exposure, the TBA-active products increased in leaves and stems (130 and 204 %, respectively). Maximum of the TBA-active products was noticed at 72^nd  h, particularly in stems. On the 7^th day of salt stress, the TBA-active products level decreased in leaves and roots, while in stems it remained at high level. Total amount of the phenolic compounds in the buckwheat roots treated with NaCl ranged from 35.55 to 64.95 µg/g DW in leaves – from 98.36 to 112.49 µg/g DW at different time points. In stems, the amount of total phenolic compounds was at the level in between 80.71 to 108.32 µg/g DW. After 48 h of NaCl impact, the total phenolic level decreased by 51 and 26 % in the roots and leaves, respectively. The same tendency was observed on the 3^rd day of the experiment. Finally, on the 7^th day the total phenolic content in roots approximated to the control level, however in leaves it was lower and in stems higher than in control. Content of the phenolic compounds was significantly higher in the above ground parts. An increase of the anthocyanin content during the long-term exposure to the stress was consistent with the statement regarding their secondary response to overcome an oxidative stress. Salt shock adversely affected physiological activity of the buckwheat plants whereas a decrease of the TBA-active products, and a restoring of phenolics quantity in plant organs under prolonged salt stress points to an activated adaptive response.