[Evaluation of the malate dehydrogenase activity in deteriorated sunflower seeds]

Malate dehydrogenase (MDH) activity in sunflower (Helianthus annus L. cv. Peredovik) seeds stored at 65 degrees C and 90 degrees C for 1, 3, 5, 7, and 14 days was evaluated. This study was design to discern the usefulness of this viability test for deteriorated seeds. Differences in the resistance to the heat storage were detected between treatments as reflected by changes in the evolution of MDH activity. A decrease of MDH activity in both soluble and mitochondrial fractions was observed, which was more evident in seeds stored at high temperature. These differences are poorly correlated to viability as determined by tetrazolium staining, and should be related to integrity of cellular membranes as evidenced by differential MDH activity in soluble and mitochondrial fractions.