BERMUDAGRASS GROWTH, TOTAL NONSTRUCTURAL CARBOHYDRATE CONCENTRATION, AND QUALITY AS INFLUENCED BY NITROGEN AND POTASSIUM

Hybrid bermudagrass cultivars (Cgnodon dactylon L, x C. trans-vaalensi s Burtt-Davy) differ in their responses to N and Ii for growth, total nonstructural carbohydrate (TNC) concentration, and turf quality score s. This 1995 research was conducted in Florida to compare responses of two bermudagrass cultivars to N and K under long-dal (>13 h) and shor t-day (<13 h) conditions in a glasshouse. Evaluations were made concer ning shoot and root growth, TNC concentration, and quality scores of ' FloraDwarf' and 'Tifdwarf' bermudagrass during establishment in a coar se sand medium. Experimental design under each photoperiod was a rando mized complete block with factorial treatments consisting of two culti vars, four rates of N, four rates of K, and four replications. Data we re analyzed by fitting multiple regression equations starting with a s econd order polynomial model. Growth of FloraDwarf was highly responsi ve to photoperiod, in that decreased daylengths reduced growth. No gro wth differences were found in Tifdwarf due to daylength. Growth increa sed in response to N in both cultivars, while growth response to Ii va ried by cultivar, Both cultivars accumulated higher levels of TNC unde r short day conditions,,vith higher levels in FloraDwarf. Nitrogen fer tilization reduced TNC levels in FloraDwarf under short days and in Ti fdwarf under long days, while K fertilization reduced TNC levels in Ti fdwarf under short days, Quality scores in both cultivars increased in response to N under long days, and in response to both N and K under short days. Results of these studies indicated that growth, TNC accumu lation, and quality differed due to cultivar, photoperiod, and rates o f N and K.