Thermal regulation of secondary dormancy induction in Polygonum aviculare seeds: a quantitative analysis using the hydrotime model

DIEGO BATLLA; ANDRES AGOSTINELLI

Congreso; 11th Conference of the International Society for Seed Science; 2014

International Seed Science Society

The effect of temperature on dormancy release of has been studied and quantified in seeds of many species, however much less is known about how temperature regulates induction into secondary dormancy. The objectives of the present work were (1) to quantify the effect of temperature on the induction of secondary dormancy in P. aviculare seeds and (2) to develop a model to simulate changes in germination dynamics during dormancy induction in relation to temperature. To achieve these objectives P. aviculare seeds previously stratified at 5ºC to reduce their primary dormancy level were stored under moist conditions at temperatures of 10, 15, 20 and 25ºC to provoke induction of secondary dormancy. After stratification and at regular intervals during storage at dormancy inductive temperatures seeds were exhumed and incubated under different temperatures (10, 15, 20 and 10/20) and water potential solutions (0, -0.2 and -0.4 MPa). Hydrotime model parameters mean base water potential (Ψb (50)), hydrotime (θH) and deviation of base water potential (σΨb), were calculated based on obtained germination data. Induction into dormancy during storage was verified as an increase in Ψb (50), and was dependent on storage temperature where the higher the temperature the faster the increase in Ψb (50). This decrease in Ψb (50) was described by an exponential increase function, in which the parameter K is the rate of increase of Ψb (50). The relationships between K and storage temperature was adequately described by a bilinear model, in which seeds stored at 25 C showed a higher rate of dormancy induction than those stored in the range 10-20C. θH and σΨb showed a decrease during storage at dormancy inductive temperatures and a bilinear model similar to the one of Ψb (50) was developed. The developed simulation model shows a good description of germination data. On the other hand the higher rates of dormancy induction in relation to those observe for dormancy release suggest that this can be a important process governing seed emergence in the field.