This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Gusta, L. V. Articles by Stout, D. G. Search for Related Content PubMed PubMed Citation Articles by Gusta, L. V. Articles by Stout, D. G. Agricola Articles by Gusta, L. V. Articles by Stout, D. G.

Articles

A Nuclear Magnetic Resonance Study of Water in Cold-acclimating Cereals ¹

David B. Russell^b

Darryl G. Stout^2,c

^a Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0W0 Canada, Department of Chemistry and Chemical Engineering, University of Saskatchewan, ^c Crop Science Department, University of Saskatchewan

Continuous wave nuclear magnetic resonance (NMR) studies indicated that the line width of the water absorption peak (v) from crowns of winter and spring wheat (Triticum aestivum L.) increased during cold acclimation. There was a negative correlation between v and crown water content, and both of these parameters were correlated with the lowest survival temperature at which 50% or more of the crowns were not killed by freezing (LT₅₀). Regression analyses indicated that v and water content account for similar variability in LT₅₀. Slow dehydration of unacclimated winter wheat crowns by artificial means resulted in similarly correlated changes in water content and v. Rapid dehydration of unacclimated crowns reduced water content but did not influence v. The incubation of unacclimated winter wheat crowns in a sucrose medium reduced water content and increased v. The increase in v appears to be dependent in part on a reduction in water content and an increase in solutes.

Longitudinal (T₁) and transverse (T₂) relaxation times of water protons in cereals at different stages of cold acclimation were measured using pulse NMR methods. The T₁ and T₂ signals each demonstrated the existence of two populations of water, one with a short and one with a long relaxation time. During the first 3 weeks of acclimation, the long T₂ decreased significantly in winter-hardy cereals, and did not change in a spring wheat until the 5th week of hardening. There was no change in the long T₁ until the 3rd week of hardening for the winter cereals and until the 7th week of hardening for the spring wheat. No simple relationship could be established between T₁ or T₂ and cold hardiness. Neither continuous wave or pulsed NMR spectroscopy can be used as a diagnostic tool in predicting the cold hardiness of winter wheats. An increase in v or a reduction in relaxation times does not provide evidence for ordering of the bulk of the cell water.

¹ Research was supported in part by the National Research Council of Canada Grant A-9661.