THE DELETERIOUS EFFECTS OF HIGH-TEMPERATURE DURING EARLY GERMINATION ON MEMBRANE INTEGRITY AND SUBSEQUENT GERMINATION OF AMARANTHUS-LIVIDUS

The effects of high temperature treatment on Amaranthus lividus seeds during the early imbibitional phase were studied in terms of germinati on behaviour, leakage of W-absorbing substances, electrolyte leakage a nd free radical mediated membrane deterioration. Transfer of seeds dur ing the early imbibitional period from 25 degrees C to 45 degrees C fo r 4, 8, 12 and 16 hours resulted in the leakage of UV-absorbing substa nces and electrolytes up to 72 hours. Leakage of alpha-NH2 and soluble carbohydrates was measured and the relative leakage ratio and membran e injury index were calculated. High temperature treatment decreased e thylene formation in germinating seeds. It is suggested that high temp erature caused greater membrane damage by membrane lipid per oxidation in germinating seeds. This is substantiated by the elevated level of malondialdehyde and higher lipoxygenase activity in high temperature t reated germinating seeds. Involvement of free oxygen radicals in membr ane deterioration in the germinating seeds under heat shock could be i ndirectly inferred by the reduced activities of free radical scavenger s like peroxidase, catalase and superoxidedismutase, with a concomitan t rise in free H2O2 level.