Relationship between guard cell length and cold hardiness in wheat

Abstract

Identification of plant characters associated with cold tolerance is useful for the development of plant-breeding selection procedures and understanding the underlying mechanisms of cold hardiness. This research investigates the association of guard cell length with cold tolerance and examines the relationship between cell size, as estimated from guard cell length, and other characters previously found to be highly correlated with cold tolerance in wheat (Triticum aestivum L. em. Thell.). Guard cell length was compared with field survival, LT50, tissue water content, and plant erectness of cultivars representing a wide range of cold tolerance levels. The three most cold-tolerant cultivars had the smallest cells, while the cultivar with the largest cell size was a spring type. There were significant (P ≤ 0.05) correlations between guard cell length and all cold-tolerance-related characters considered. Differences in guard cell length were most closely related to field survival as measured by Field Survival Index (FSI). Stepwise regression analysis indicated that cell size explained 45% of the variability in FSI. Cell size combined with plant erectness and tissue water content explained 88% of the variability in FSI. LT50 and cell size together explained 96% of the variability in FSI. The effects of cell size on cold hardiness may relate to its influence on cell water content and cellular mechanical stress during intercellular ice-crystal formation and freezing-induced dehydration. Guard cell size should be a useful selection tool in cultivar development programs that have increased cold hardiness as the breeding objective. Key words:Triticum aestivum, winter wheat, cold hardiness, guard-cell length, cell size