EFFECT OF THERMAL STRATIFICATION CONDITIONS DURING DORMANCY RELEASE ON THE RATE OF INDUCTION INTO SECONDARY DORMANCY IN Polygonum aviculare L. SEEDS

CRISTIAN MALAVERT; DIEGO BATLLA; ROBERTO LUIS BENECH-ARNOLD

Changsha, Hunan

Congreso; The 11th Conference of the International Society for Seed Science (ISSS); 2014

International Society for Seed Science (ISSS)

p { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); }p.western { font-family: "Times New Roman",serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans","MS Mincho"; font-size: 12pt; }p.ctl { font-family: "Lohit Hindi","MS Mincho"; font-size: 12pt; }a.western:link { }a.ctl:link { } In seeds of many summer annual weeds low temperatures under moist conditions provoke dormancy release while high temperature induce secondary dormancy. These changes in seed dormancy level establish changes in the thermal range permissive for germination. In summer annual seeds changes in the thermal range permissive for germination are a consequence of changes in the lower limit temperature (Tl) for seed germination. Numerous studies has been conducted on the characterization of temperature on the primary dormancy release, however, it has not been evaluated how stratification temperature affects the subsequent rate of induction into secondary dormancy. The aim of this work was to characterize the role of stratification temperature on the induction of secondary dormancy in seeds of P. aviculare. To achieve this objective seeds of P. aviculare were stratified at different temperatures (1.6, 5 and 10°C) to a minimum level of dormancy. When the seeds had a minimum level of dormancy they were induced into secondary dormancy at 20°C. The results showed that the rate of induction into secondary dormancy was higher for seeds that were stratified at 1.6°C compared to those that were stratified at 5 and 10°C. The differential patterns of change that resulted from each stratification temperature could be explained by a differential change in the standard deviation of Tl at the end of the stratification period. Stratified seeds at 1.6°C showed a deviation of 1.5, which determines a lower fraction of the seed population able to germinate, however, seeds stratified at 5 and 10°C, showed a higher deviation and the fraction that germinate is greater; this determines an apparent slower induction into secondary dormancy. Obtained results showed that the temperature experienced by the seeds during dormancy loss can affect the subsequent rate of induction into secondary dormancy and that these effects could be explained by changes in the standard deviation of the Tl permissive for seed germination.