Thermal regulation of dormancy in Echinochloa crus‐galli (L.) P. Beauv. seeds: Development of a model to predict the temporal ‘window’ of emergence in the field

Abstract

Predicting weed emergence is of vital importance for weed management, since the seedling stage is the most effective plant stage for the application of control practices. In weeds species whose seeds present dormancy, as in Echinochloa crus‐galli, predicting emergence requires understanding how the environment regulates seed dormancy level. In the present work we studied the environmental regulation of dormancy in E. crus‐galli seeds. For this, E. crus‐galli seeds were stored under different conditions: (i) moist at 5, 10 and 15°C (stratification) and (ii) dry at 15 and 25°C (dry after‐ripening) for 80 days. During storage the seeds were tested for germination at regular intervals under a wide thermal range (10–30°C). The results showed that the changes in dormancy level were associated with a widening of the thermal range permissive for seed germination, which was mainly explained by a decrease in its lower limit temperature (Tl). This decrease in Tl was higher when the seeds were stratified at 10°C than at 5 and 15°C. Seeds exposed to dry after‐ripening showed an extremely low rate of dormancy release. Obtained results were used to establish functional relationships able to predict the temporal ‘window’ of field emergence of E. crus‐galli as a function of soil temperature.