Chemical Changes Occurring in Three Bermudagrass Turf Cultivars in Relation to Cold Hardiness1
- J. H. Dunn and
- C. J. Nelson2
Susceptibility to winter injury has limited the use of bermudagrass (Cynodon sp.) to a few hardy cultivars in the “upper” South which is an environmental transition area for turfgrass species. An understanding of the nature of winter hardening and the basis for winter injury in bermudagrass would give turf breeders a key to the development of winter-hardy cultivars which are adapted for use as turf in transition areas where winter injury is like to occur. The purpose of this study was to compare three bermudagrass cultivars differing in winter survival morphologically and by chemical composition. The ‘U-3’ cultivar was less cold hardy under conditions of the artificial freeze test than the ‘Midway’ and ‘Westwood’ cultivars at several sampling dates during the fall and winter. Midway had more rhizome and stolon tissue per unit area than the other cultivars which may give it some advantage for winter survival. Rhizomes of Westwood were thicker than those of Midway or U-3. Total carbohydrates and sucrose increased in rhizomes and stolons during fall as hardening occurred. During winter sucrose increased slightly and reducing sugars remained constant while starch and total carbohydrate decreased. Carbohydrate differences among cultivars were slight and not related to winter survival. Stolons appeared to be the principal overwintering storage organ for carbohydrates and source of energy for regrowth in spring. Concentrations of total nitrogen, αNH2-N, and nitrate N in overwintering tissue appeared to be dependent on the growth activity of the plants during fall and the date of the first killing frost. The U-3 cultivar had higher total N, αNH2-N and NO3-N than the other cultivars. Ranking of cold hardiness of bermudagrass cultivars may be possible by combining morphological and chemical composition features into an index.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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