Ethanol and hormones in physiological conditioning on germination and seed dormancy of Urochloa humidicola cv. Llanero

Abstract: Seed conditioning improves germination uniformity, speed, and dormancy release. This work aimed the study the physiological conditioning of Urochloa humidicola cv. Llanero, using two lots of dormant seeds conditioned by imbibition with water, commercial bioregulator (auxin, gibberellin - 0.144 mM and cytokinin), gibberellin (0.144 and 1.44 mM) or 5% ethanol. Germination, dormancy, SOD activity, MDA and H2O2 content were evaluated. In both lots, germination percentage was positively influenced by the commercial bioregulator without affecting the viability. In the first, the germination, using a bioregulator or ethanol, was higher; in the second, the highest germination was from the treated seeds concerning the control and water treatment. The unconditioned seeds presented a higher H2O2 and protein content in both lots. The MDA content in the first lot was higher in the non-conditioned seeds and conditioned with ethanol. In the second lot, the water conditioned seeds had higher content. In both lots, the bioregulator conditioned seeds showed higher SOD activity. The H2O2 content was related to antioxidation activation. It was impossible to identify the oxidative window of germination in which H2O2 would be a signal, releasing germination. The conditioning of seeds with any product showed superior physiological quality than the unconditioned or conditioned with water.