Germination parameterization and development of an after-ripening thermal-time model for primary dormancy release of Lithospermum arvense seeds.

CHANTRE, GUILLERMO RUBÉN; BATLLA, DIEGO; SABBATINI, MARIO RICARDO; ORIOLI, GUSTAVO

ANNALS OF BOTANY

OXFORD UNIV PRESS

Año: 2009 vol. 103 p. 1291 - 1301

0305-7364

·        Background and Aims: Models based on thermal-time approaches have been a useful tool for characterizing and predicting seed germination and dormancy release in relation to time and temperature. The aims of the present work were to evaluate the relative accuracy of different thermal-time approaches for the description of Lithospermum arvense germination and to develop an after-ripening thermal-time model for predicting L. arvense seed dormancy release. ·        Methods: Seeds were dry-stored at constant temperatures of 5, 15, and 24°C for 210 days. After different storage periods, batches of 50 seeds were incubated at eight constant temperature regimes of 5, 8, 10, 13, 15, 17, 20 and 25°C. Experimentally obtained cumulative-germination curves were analyzed using a non-linear regression procedure to obtain L. arvense optimal population thermal parameters. Changes in these parameters were described as a function of after-ripening thermal-time and storage temperature. ·        Key Results: The most accurate approach for simulating L. arvense thermal-germination response was achieved by assuming a normal distribution of both base and maximum germination temperatures. Our results contradict the widely accepted assumption of a single Tb value for the entire seed population. The after-ripening process was characterized by a progressive increase in the mean maximum germination temperature and a reduction in the thermal-time requirements for germination at sub-optimal temperatures. ·        Conclusions: The developed after-ripening thermal-time model gave an acceptable description of the observed field emergence patterns, thus indicating its usefulness as a predictive tool to enhance weed management tactics. Key words: Lithospermum arvense, winter annual weed, thermal-time model, cardinal temperatures, primary dormancy, after-ripening thermal-time, storage temperature, field germination, seedling emergence.