Hydropriming as a pre-treatment for cotton germination under thermal and water stress conditions

Laboratory experiments demonstrated that hydropriming increased the speed of germination in cotton, which is grown commercially in many semiarid regions worldwide. In these areas, where precipitations are sparse and irregular, temperature and water stress are frequent factors inhibiting cultivation. The thermal time model, used widely to characterize the germination and seed vigour of many species other than cotton, was used in determining the effects of hydropriming on cottonseeds experiencing a variety of stress conditions. The objectives in this study were: a) to evaluate cotton germination at different temperatures and water potentials, including the changes induced by hydropriming, b) to calculate the thermal time model's parameters for both control and hydroprimed seeds and c) to assess the effects of hydropriming on seed vigour. To evaluate the effects of hydropriming, germination for both control and hydroprimed seeds was analyzed at different water potentials and temperatures. The germination time courses at varying temperatures were analyzed according to the thermal time model; moreover, hydropriming accelerated germination significantly, compared to control seeds, reduced the thermal time required for radicles to emerge and improved seed vigour.