Physiological and biochemical changes during desiccation tolerance loss in millet (Pennisetum glaucum L.) seeds

ABSTRACT. The aim of this study was to evaluate the physiological and biochemical changes related to desiccation tolerance loss in millet seeds. The studied points of the germination process were determined according to the seed imbibition curve of the millet hybrid ADRF6010: control (0h), 3h of imbibition, 1 and 3 mm radicle. The seeds were dried on silica gel for 72h at 20°C, followed by pre-humidification at 25°C for 24h. Seed physiological quality was evaluated by electrical conductivity and a germination test, and seed vigor was evaluated with a first germination count and a germination speed index. The experiment was performed in a completely randomized design, and means were compared by the Scott-Knott test at a 5% probability. The enzymatic systems of superoxide dismutase, catalase, peroxidase, and α-amylase, as well as the expression of heat-resistant proteins were evaluated. Enzymatic activity was quantified with the ImageJ® software. Millet seeds lost desiccation tolerance when the radicle reached 1 mm in length. According to enzymatic standards, peroxidase and α-amylase activity, as well as heat-resistant protein activity, were related to desiccation tolerance loss in millet seeds.