Effect of seed water content during stratification on dormancy release in Polygonum aviculare l. seeds

CRISTIAN MALAVERT; DIEGO BATLLA; BENECH-ARNOLD, ROBERTO

Congreso; XXII Congreso Latinoamericano de Malezas; 2015

The number of established seedlings and time of weed emergence is strongly related to the dynamics of dormancy release of the seed-bank. Changes in the level of dormancy in the seed bank are exposed to different stimuli from several environmental factors simultaneously. The main regulatory factor is temperature, but it is not known exactly how this effect is modulated by the seed hydration level determined by soil water content. The aim of this work was to study the effect of water content during stratification period on dormancy release rate in P. aviculare seeds. To measure the effect of water content, seeds of P. aviculare were stored at 5 °C during 100 days (thermal stratification conditions for dormancy release) under controlled conditions of relative humidity (%RH) of 5 %RH (ZnCl2), 15 %RH (LiCl), 61 %RH (Ca(NO3)2), 75 %RH (NaCl), 88 %RH (KCl), 96 %RH (KNO3), 100%RH (H2O) and imbibed seeds; under these conditions moisture content values in the seeds of 6.7, 7.6, 11.4, 13.4, 15.8, 22, 29.8 and 35.1 % were obtained respectively. Results obtained showed the existence of a lower water content threshold of 15 % in the seed below which no dormancy release takes place. Seed water content values above this threshold promoted the effect of stratification temperature on dormancy release, showing an increase in the dormancy loss rate with increasing seed water contents, reaching a plateau above 29.8 %. The results obtained in this study are among the first to quantify the effect of seed moisture content during the stratification period on the dormancy release rate. These results could be incorporated into existing predictive models to take into account the effect of soil water content on the dormancy loss process.