Hydropriming changes temperature thresholds for seed germination of tree species from the Caatinga, a Brazilian tropical dry forest

Abstract: This study evaluates the effects of hydration and dehydration cycles (HD cycles) on seed germination four Caatinga tree species (Anadenanthera colubrina var. cebil, Enterolobium contortisiliquum, Pityrocarpa moniliformis Pterogyne nitens) subjected to different temperatures determine thermal upper lower limits germination. For this, seeds were 0, 1, 2 3 HD set germinate at 5, 10, 15, 25, 35, 40 45 °C. Germinability t50 calculated differences these parameters compared by two-way ANOVA. In addition, rate (GR = 1/t50), as well ceiling (Tc), optimum (To) base (Tb) estimate below or above which fail germinate. We observed that more cycles, better responds, especially extreme temperatures. Seeds all studied showed To between 25 35 °C, Tb < 10 Tc > The slope regression curves for submitting expands its tolerance range, revealing this pre-treatment can be efficient it increases their stress.