LAUSR

Seeds may differ in terms of dormancy, longevity, sensitivity to desiccation, and dry mass, according to the period of diaspore dispersal. In addition, seasonal variations in temperature and water availability can act as signs of the season during seed development, influencing germination responses and root growth. We evaluated the effects of temperature variations and water availability on germination parameters, root growth, and seed traits of four coexisting Piper species in seasonal vegetation that differ in terms of diaspore dispersal period. Eight temperature treatments (15, 20, 23, 25, 28, 30, 35°C, and alternate of 30°C-20°C) and four induced water potentials (0, -0.3, -0.6, and -1.2 MPa) were used. The parameters germination onset, germination percentage (G%), mean germination time (MGT), root elongation, seed longevity during ex situ storage, and dry mass of seeds were evaluated. Germination responses observed were independent from the diaspore dispersal period, such as the variations in germination onset, G%, and MGT, both in temperature and water availability treatments. Contrastingly, root elongation, longevity and dry mass of seeds varied according to the period of diaspore dispersal. Our results corroborate the hypothesis that the period of diaspore dispersal is an important factor in controlling the initial development of seedlings in seasonal vegetation, but not in germination responses. The predominance of negative effects of temperature increases and water deficit on root growth shows that the initial stages of plant development can be strongly impacted by these environmental factors.