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Title: FREEZING IN NON ACCLIMATED OATS: THERMAL RESPONSE AND HISTOLOGICAL OBSERVATIONS OF CROWNS DURING RECOVERY

Author
item Livingston, David
item TALLURY, SHYAMALRAU - NORTH CAROLINA STATE UNIV
item Premakumar, Ramaswamy

Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2004
Publication Date: 4/10/2006
Citation: Livingston, D.P., Tallury, S.P., Premakumar, R. 2006. Freezing in non acclimated oats: thermal response and histological observations of crowns during recovery. Canadian Journal of Botany 84:199-210.

Interpretive Summary: Freezing stress in plants is a complex phenomenon which can be better understood if the process is simplified. Studying freezing in non-hardened plants at temperatures just below freezing provides a system in which few, if any, hardening processes have been initiated in plants. We compared freezing patterns (area under curves as well as curve shape) of model systems to freezing curves of live plants in crowns of the least freezing tolerant cereal, oat in an isothermal calorimeter at -2C. Pure water froze within 30 min and the addition of filter paper significantly altered the shape of the curve. Freezing curves of plants more closely resembled those of fructan and sugar solutions with filter paper. The more freezing tolerant cultivar Wintok reached 50% survival after 4 days in cold hardening and the less freezing tolerant cultivar took nearly 14days. During cold-hardening the percentage of water freezing went from 79% in the more hardy cultivar to 54% during 3 weeks of cold hardening. The less hardy cultivar had a similar trend but the percentage of water freezing was higher. Possible relationships to freezing tolerant mechanisms are discussed.

Technical Abstract: Freezing stress in plants is a complex phenomenon which can be better understood if the process is simplified. Studying freezing in non-hardened plants at temperatures just below freezing provides a system in which few, if any, hardening processes have been initiated in plants. We compared freezing patterns (area under curves as well as curve shape) of model systems to freezing curves of live plants in crowns of the least freezing tolerant cereal, oat in an isothermal calorimeter at -2C. Pure water froze within 30 min and the addition of filter paper significantly altered the shape of the curve. Freezing curves of plants more closely resembled those of fructan and sugar solutions with filter paper. The more freezing tolerant cultivar Wintok reached 50% survival after 4 days in cold hardening and the less freezing tolerant cultivar took nearly 14days. During cold-hardening the percentage of water freezing went from 79% in the more hardy cultivar to 54% during 3 weeks of cold hardening. The less hardy cultivar had a similar trend but the percentage of water freezing was higher. Possible relationships to freezing tolerant mechanisms are discussed.