PHYSIOLOGICAL AND BIOCHEMICAL PERFORMANCE OF CUCUMBER SEEDS AT DIFFERENT MATURATION STAGESABSTRACT -The objective iN this study was to evaluate the physiological and biochemical performance of cucumber seeds during the maturation process. The cucumber seeds of the hybrid "Ômega" were used and the fruits were harvested at 30, 35, 40, 45, 50 and 55 days after anthesis. The seed quality was assessed after processing and drying, by measuring fruit mass, water content, seed dry mass and mass of thousand seeds. The seed physiological quality was evaluated from the tests of germination, first counting, electrical conductivity, speed emergence index, and final stand. X-ray and electrophoresis analyses of the iso-enzymes superoxide dismutase, catalase, esterase, lipoxigenase, isocitrate liase and LEA proteins were made. An improved physiological quality of hybrid Omega cucumber seeds is obtained at 45 and 50 days after anthesis, when the fruits are greenish-white. This is supported by analysis of superoxide dismutase, catalase, lipoxygenase, isocitrate lyase and LEA proteins, as well as the X-ray test, which confirmed the results of the physiological tests.