CHANGES IN TOTAL POLYPHENOLS, FLAVONOIDS, PHOTORESPIRATION, RESPIRATION AND GLYCOLATE OXIDASE ACTIVITY IN MAIZE PLANTS GERMINATED FROM SEEDS EXPOSED TO FREEZING STRESS
Maria CAUS*, Nicolai PLATOVSCHII
Abstract
The aim of this study was to investigate the post-freezing effect of -4°C for 16 h (FS) applied to soaked maize seeds before germination on the levels of total polyphenols (TPC) and total flavonoids (TFC), photorespiration, total respiration and dark respiration, glycolate oxidase (GO) activity in maize plants grown under dark and light conditions. Exposure of maize seeds to subzero temperatures before germination followed by growth in the dark or in the light revealed after-effects of these factors on both TPC and TFC. The greatest inhibition of TPC by FS was achieved in etiolated sprouts (≈10%) and in 6-day-old plants in the light (≈9%), while the lowest level of TPC was observed in leaves of 8- and 17-day-old plants under light conditions. Photorespiration, total respiration, dark respiration, and glycolate oxidase activity in maize plants grown from seeds exposed to FS remained at reduced levels than in control samples. The suppression of these indices, apparently, in this case may be associated with a slowdown in the intensity of photosynthetic gas exchange in general.