Growth Responses of Tall Fescue and Bermudagrass to Leaf Applications of Ancymidol1
- C. J. Nelson,
- J. H. Dunn and
- J. H. Coutts2
Growth inhibitors are used for topgrowth control of turfgrasses, but little information exists on associated physiological responses or growth of other plant parts. Therefore, experiments were conducted with ancymidol and an analog to assess their potential as growth retardants and their effects on physiological processes associated with vigor and tolerance to environmental stress.
Tall rescue (Festuca arundinacea Schreb.) and bermudagrass [Cynodon dactflon (L.) Pers.] were grown under controlled environment conditions, and regrowth was measured for up to 32 days following application of foliar sprays of inhibitor. Topgrowth of bermudagrass was almost stopped at concentrations of ancymidol above 100 ppm, whereas tall rescue gave a quantitative growth response over the 200 to 600 ppm range. Root weight of treated bermudagrass was less than the control after a 21-day regrowth period, but not when the growth period was 32 days. Root growth of tall rescue was not affected by treatment. Stubble weight of bermudagrass, which included leaf and stem tissue up to 6 cm above soil level, tended to be increased by treatment. Stubble weight of tall rescue was unaffected. Stolon number and weight were reduced about 50% by treatment of bermudagrass whereas tiller number of tall rescue was increased up to 30%.
Concentration of storage carbohydrate was reduced 10 to 20% in stubble and stolons of treated bermudagrass, and 25 to 40% in all tissue of treated tall rescue. This probably occurred because net CO2 exchange per pot was usually reduced by treatments due to decreased leaf area. Net CO2 uptake of both species on a leaf area basis was unaffected. Water use per pot per day was 20 to 25% lower in treated plants.
Results suggest that short-term growth control may be feasible to reduce transpiration. Long term control, such as slowing growth in fall to increase frost resistance, may also be possible. However, in this study storage carbohydrate levels were lower than controls, and thus plants may not be vigorous enough to maintain themselves over long time intervals.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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