Bermudagrass Growth, Total Nonstructural Carbohydrate Concentration, and Quality as Influenced by Nitrogen and Potassium

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1 168 CROP SCIENCE, VOL. 38, JANUARY FEBRUARY 1998 Sprague, N.B., and G.W. Burton Annual bluegrass (Poa annua ) Timm, G Biology and systematics of Poa annua L. Zeitscrhift and its requirements for growth. New Jersey Agric. Exp. Stn. Fur Ackerund Pflazenbau 122: Bull Tutin, T.G A contribution to the experimental taxonomy of Steel, R.G.D., and J.H. Torrie Principles and procedures of Poa annua L. Watsonia 4:1 10. statistics. McGraw-Hill, New York. Wells, G.J The biology of Poa annua and its significance in Till-Bottraud, I., L. Wu, and J. Harding Rapid evolution of grassland. Herbage Abstracts 44: life history traits in populations of Poa annua L. J. Evolutionary Biol. 3: Bermudagrass Growth, Total Nonstructural Carbohydrate Concentration, and Quality as Influenced by Nitrogen and Potassium L. E. Trenholm,* A. E. Dudeck, J. B. Sartain, and J. L. Cisar ABSTRACT ential responses to N and K fertilization rates. Liberal Hybrid bermudagrass cultivars (Cynodon dactylon L. C. transbermudagrass N fertilization has increased shoot growth in numerous vaalensis Burtt-Davy) differ in their responses to N and K for growth, cultivars (Burton and Jackson, 1962; Wil- total nonstructural carbohydrate (TNC) concentration, and turf qual- kinson and Langdale, 1974). Enhanced shoot growth ity scores. This 1995 research was conducted in Florida to compare has been at the expense of root growth in various turf responses of two bermudagrass cultivars to N and K under long-day species (Adams et al., 1974; Goss and Law, 1967; Madi- ( 13 h) and short-day ( 13 h) conditions in a glasshouse. Evaluations son, 1962), although Horst et al. (1985) reported inwere made concerning shoot and root growth, TNC concentration, and creased root growth in response to N at rates up to 4.9 quality scores of FloraDwarf and Tifdwarf bermudagrass during gm 2 per growing month on Santa Ana bermudagrass. establishment in a coarse sand medium. Experimental design under Potassium at rates up to 22.4 g K m 2 yr 1 increased each photoperiod was a randomized complete block with factorial treatments consisting of two cultivars, four rates of N, four rates root or rhizome weights in Coastal bermudagrass (Kei- of K, and four replications. Data were analyzed by fitting multiple sling et al., 1979). Shoot growth in Coastal increased regression equations starting with a second order polynomial model. with up to 14.0 g K m 2 (Belesky and Wilkinson, 1983) Growth of FloraDwarf was highly responsive to photoperiod, in that and up to 41.9 g m 2 (Cripps et al., 1989). Tifton 44 decreased daylengths reduced growth. No growth differences were increased shoot and root growth in response to 14.0 g found in Tifdwarf due to daylength. Growth increased in response to Km 2 (Belesky and Wilkinson, 1983). N in both cultivars, while growth response to K varied by cultivar. Differential responses also have been reported for Both cultivars accumulated higher levels of TNC under short day quality in response to N and K. Quality and density in conditions, with higher levels in FloraDwarf. Nitrogen fertilization Tifway increased up to 20 g N m 2 yr 1 (Johnson et al., reduced TNC levels in FloraDwarf under short days and in Tifdwarf under long days, while K fertilization reduced TNC levels in Tifdwarf 1987) and promoted early spring green up in Tifgreen under short days. Quality scores in both cultivars increased in response (Reeves et al., 1970). Potassium fertilization has in- to N under long days, and in response to both N and K under short creased resistance to cultural stresses such as wear, soil days. Results of these studies indicated that growth, TNC accumulation, compaction, and cold temperatures (Carrow et al., 1987; and quality differed due to cultivar, photoperiod, and rates of Juska and Murray, 1974). N and K. Information on responses of warm-season grasses to N and K during establishment is limited. Maximum establishment of nine bermudagrass cultivars was H ybrid bermudagrass cultivars provide high qual- achieved with 4.8 g N m 2 mo 1, with a reduction in ity turf for athletic surfaces in warm climates. rate of establishment when N was applied at 6.2 g m 2 Quality in these cultivars is characterized by a compact, mo 1 (Dudeck et al., 1985). Juska (1959) found that dense, and uniform growth habit. In addition to these Meyer zoysiagrass (Zoysia japonica Steud.) increased morphological features, quality also is characterized by top and stolon growth during establishment in response the capacity of the turf to tolerate stresses such as to K at 20.6 g m 2 yr 1, but Fry and Dernoeden (1987) drought, temperature, traffic, and low cutting heights. found few differences during establishment in response Although the hybrid cultivars are closely related, growth to K up to 10.3 g m 2 yr 1. habit, morphology, and responses to cultural practices Concentration of N and K in tissue has influenced may differ between them. total TNC reserves (Adams et al., 1967; Goatley et al., Bermudagrass cultivars have previously shown differences 1994; Miller and Dickens, 1996) and intraspecific differ- in TNC concentration have occurred in bermu- L.E. Trenholm and A.E. Dudeck, Environmental Horticulture Dep., dagrass (Miller and Dickens, 1996). Carbohydrate accu- J.B. Sartain, Soil and Water Science Dep., Univ. of Florida, Gainesville, FL ; and J.L. Cisar, Environmental Horticulture Dep., N-enhanced growth (Adams et al., 1967; Goatley et mulation is inversely related to N fertilization due to Univ. of Florida, Ft. Lauderdale REC, Ft. Lauderdale, FL al., 1994; Schmidt and Blaser, 1969; Walker and Ward, Florida Agric. Exp. Stn. Journal No. R Received 8 Apr ). Total nonstructural carbohydrates decreased in *Corresponding author (ltren@uga.cc.uga.edu). Published in Crop Sci. 38: (1998). Abbreviations: TNC, total nonstructural carbohydrate.

2 TRENHOLM ET AL.: BERMUDAGRASS GROWTH, CARBOHYDRATE CONCENTRATION, AND QUALITY 169 roots and rhizomes of Tifdwarf and Tifway bermutransplanting, cm in diam. using the media previously described. Following dagrass in response to increasing rates of K (Miller and shoot growth was mowed to a uniform height of Dickens, 1996). Tifdwarf had higher concentrations. Poaveraged 0.64 cm. with an electric hand-held rotary mower. Photoperiod 13.6 h d 1 during the long-day study and 12.1 h d 1 tassium had no effect on shoot and stolon TNC concenduring the short-day study. Average light intensities during trations. Tifgreen bermudagrass (Goatley et al., 1994) the long-day study were 1212 E m 2 s 1 daily and 950 E m and centipedegrass [Eremochloa ophiuroides (Munro) 2 s 1 daily during the short-day study. Glasshouse temperatures Hack.; Walker and Ward, 1974] showed no differences were controlled and averaged 34.4 and 33.8 C during longin TNC concentration in response to K. and short-day studies, respectively. Irrigation was provided to Carbohydrate accumulation also is influenced by sea- supply uniform rates of overhead water daily and was adjusted sonal effects. Concentration of TNC increased in three as needed to maintain leaf turgor. bermudagrass cultivars from September through Noat Nitrogen treatments were supplied as ammonium nitrate vember (Dunn and Nelson, 1974). Miller and Dickens the following rates in the long- day study: 1.2, 2.4, 4.9, and (1996) reported increased TNC levels in bermudagrass 9.8 g m 2 mo 1. Rates were modified to the following in the grown in Alabama from June through September. Midwas supplied as potassium chloride at the following rates for short-day study: 2.4, , and 9.8 g m 2 mo 1. Potassium iron bermudagrass had decreased starches in roots and both studies: 0.6, 1.2, 2.4, and 4.9 g m 2 mo 1. Stock fertilizer, stolons from September to November, while sugars in- containing other essential macro- and micronutrients, was apcreased during this time (White and Schmidt, 1990). plied concurrently with treatments. All treatments were ap- Other environmental factors, such as photoperiod at plied weekly and were preceded by leaching pots with 75 ml time of establishment, also may affect growth and mor- water 24 h prior to application. phology of bermudagrass. Burton et al. (1988) reported Shoots were harvested approximately every 4 wk. The long- that daylength was highly correlated (r 0.95) with day study had a total of four harvests, while the short-day biomass yield of Coastal bermudagrass, and that yield study had a total of three harvests. Shoot growth consisted of reduction occurred in daylengths under 13 h. Common leaf and vertical stem tissue and stolons that extended over bermudagrass had the fastest emergence and ground rims of pots. Tissue was placed in prelabeled, preweighed aluminum foil packets and dried in a forced air drier at 70 C cover when planted during longest photoperiods from for 48 h. Dry weights were recorded and tissue was stored for May to September (Keeley and Thullen, 1989). Rhifurther analysis. Shoot growth data were averaged across all zome and seed production occurred sooner under de- harvests to obtain weekly growth rates. Following termination clining daylengths. Marousky et al. (1992) reported of both studies, root tissue was harvested by removing all longer (up to 37.0 mm) leaves in nine bermudagrass roots and rhizomes from crown tissue at the soil interface. cultivars grown under long daylength ( 9 h), with no Root tissue was washed free of sand and placed in preweighed, increase in length in Tifdwarf due to photoperiod. No prelabeled aluminum foil packets. Tissue was then dried in a differences were found in stolon number or dry weight forced air drier at 100 C for 1 h, followed by drying at 70 C in any cultivars due to daylength. Gaussoin et al. (1988) for approximately 48 h. Root dry weights were recorded and reported shorter leaf blades and lighter color in bermu- data were calculated to represent weekly total root growth. Roots were analyzed for TNC following methodology dedagrass grown under reduced light intensity. scribed by Christiansen et al. (1988), which is a modification Differential intraspecific responses to both N and K of the procedure described by Smith (1981). imply that fertilizer recommendations and rates of es- Visual scores for turf quality were assigned to each treattablishment may differ between bermudagrass cultivars. ment twice weekly throughout both studies. Quality was Establishment and growth may further differ due to scored from 1 to 9, with 9 equaling ideal quality based on shoot hours of daylength. The objectives of this research were density, color, and uniformity. A score of 6 was considered therefore to evaluate shoot and root growth, TNC conings minimally acceptable quality for commercial turf. Visual rank- centration, and quality scores of two bermudagrass cultieach are reported as an average of all ratings taken throughout study. vars to N, K, and daylength during establishment in a course sand medium. Experimental design was a randomized complete block with treatments arranged as a factorial of two grasses, four rates MATERIALS AND METHODS of N, four rates of K, and four replications. Analysis of variance was performed using the General Linear Model procedure This research consisted of two consecutive studies, both with appropriate error terms included (SAS Institute, 1987). conducted in a glasshouse at the University of Florida Turfto Significance was determined at the 0.05 probability level. Due grass Envirotron, Gainesville, FL. A long-day study was initiby numerous interactions between studies, data were analyzed ated on 24 Apr and terminated on 14 Aug A shortand study and grass using Response Surface Regression (Freund day study was conducted from 2 Aug. through 5 Nov Littell, 1991; SAS Institute, 1987). The complete response Sprigs of FloraDwarf and Tifdwarf were obtained from surface model used was a second-order polynomial of the established field stands at the G.C. Horn Turfgrass Field Laboratory, form: Gainesville, FL. Propagules, which consisted of stolon y B 0 B 1 N B 2 N 2 B 3 K B 4 K 2 and leaf tissue, were planted in a coarse sand media to densely cover a 15.2 cm. in diam. pot. Sprigs were topdressed with 50 B 5 (N K) e ml of coarse sand. Media used was a coarse sand that fit the following USDA classifications: 31% very coarse sand, 52% In this model, y is the response variable, B 0 is the intercept, coarse sand, 15% medium sand, and 2% fine sand. After an B 1 N and B 3 K are linear coefficients for N and K respectively, initial acclimation period, sprigs were transplanted by removtively, B 2 N 2 and B 4 K 2 are quadratic coefficients for N and K respec- ing shoot growth and upper 2.5 cm of root growth. Propagules B 5 (N K) is the coefficient for the interaction of N were transplanted into plastic pots 15.2-cm depth and 15.2 and K and e is the experimental error term. Lack of fit of the

3 170 CROP SCIENCE, VOL. 38, JANUARY FEBRUARY 1998 Table 1. Coefficient estimates of shoot and root growth, TNC, and quality data for the fitted regression model: Predicted response 0 1 N 2 N 2 3 K 4 K 2 5 NK or a reduced form of the model for responses. Coefficient estimates Described Response r 2 in Figure Total shoot growth FD LD study *** 1A FD SD study *** 1B TD LD study *** 1C TD SD study *** 1D Root growth FD LD study *** 2A FD SD study 0.06 ns TD LD study *** 2B TD SD study *** 2C TNC concentration of root tissue FD LD Study 0.11 ns FD SD Study * 3A TD LD Study ** 3B TD SD Study C Quality (9 deal quality) FD LD study *** 4A FD SD study *** 4B TD LD study *** 4C TD SD study *** 4D *,**,*** Significant at the 0.05, 0.01, or probability levels, respectively; ns, not significant or significant at 0.10 probability level. gm 2 mo 1. Total shoot growth leaf stolon tissue mg m 2 wk 1 ; Root growth root tissue mg m 2 wk 1 ; TNC total nonstructural carbohydrates in percentage of concentration; FD FloraDwarf bermudagrass; TD Tifdwarf bermudagrass; LD long-day study; SD short-day study. second-order polynomial model was tested simultaneously. The reduced model for shoot growth of Tifdwarf ber- Only those coefficient estimates in the complete model that mudagrass in the long-day study included linear and showed a significant effect at the 0.10 level of probability or quadratic N, linear K, and the interaction of N K less on the response were considered in fitting a reduced (Table 1; Fig. 1C). Maximum predicted shoot growth model. Terms that were not significant in the full model were of 52.0 mg m 2 wk 1 was obtained with application of retained in the reduced model only when higher order coefficients were significant. For example, when a N K interaction 9.8 g N and 4.9 g K m 2 mo 1. Average shoot growth was occurred, linear effects of both terms were included in the 22.8 mg m 2 wk 1. Under short-day conditions, shoot model regardless of their level of probability. Similarly, when growth of Tifdwarf bermudagrass was influenced by a quadratic effect was found, linear effects were included (Chaparro linear N and linear and quadratic K components (Table et al., 1996). Equations of complete or reduced models 1; Fig. 1D). Greatest shoot growth of 32.3 mg m 2 wk 1 describing each response are presented in tabular form. was obtained with N at 9.8 g and K at 3.8 g m 2 mo 1. Shoot growth averaged 20.1 mg m 2 wk 1 under short RESULTS AND DISCUSSION days. Certain bermudagrass cultivars are known to be re- Shoot Growth sponsive to photoperiod (Burton et al., 1988; Gaussoin The reduced model for shoot growth of FloraDwarf et al., 1988). Previous research on FloraDwarf bermubermudagrass under long-day conditions included only dagrass indicated that it attained maximum growth durlinear effects of N (Table 1; Fig. 1A). Shoot growth ing short nights and long days (Dudeck, 1995). Signifi- averaged 22.7 mg m 2 wk 1. The reduced shoot growth cant differences were found in daylengths between the model for FloraDwarf under short-day conditions inwhich long- and short-day studies in this research (P ), cluded linear components of both N and K, as well are attributed to shoot growth reduction of Flora- as their interaction (Table 1; Fig. 1B). Greatest shoot Dwarf bermudagrass in short days. Glasshouse tempera- growth of 29.9 mg m 2 wk 1 occurred with the combinadays, ture averaged 34.4 and 33.8 C during long and short tion of 9.8 g N and 4.9 g K m 2 mo 1. Shoot growth respectively; since this was not a significant differ- averaged 13.3 mg m 2 wk 1 in the short-day study, which ence (P ), growth reduction in FloraDwarf was was a reduction of 41% from average shoot growth not affected by temperature. As reported previously under long-day conditions. (Marousky et al., 1992), Tifdwarf bermudagrass did not

4 TRENHOLM ET AL.: BERMUDAGRASS GROWTH, CARBOHYDRATE CONCENTRATION, AND QUALITY 171 Fig. 2. Influence of N (g m 2 mo 1 ) and K (g m 2 mo 1 ) on root growth during establishment in a sand medium in a glasshouse in Fig. 1. Influence of N (g m 2 mo 1 ) and K (g m 2 mo 1 ) on total consecutive studies. (A). FloraDwarf bermudagrass long ( 13 h) shoot growth (leaf and stolon tissue) during establishment in a sand days. (B). Tifdwarf bermudagrass long ( 13 h) days. (C). Tifdwarf medium in a glasshouse in consecutive studies. (A). FloraDwarf bermudagrass short ( 13 h) days. bermudagrass long ( 13 h) days. (B). FloraDwarf bermudagrass short ( 13 h) days. (C). Tifdwarf bermudagrass long ( 13 h) days. (D). Tifdwarf bermudagrass short ( 13 h) days. mudagrass (Horst, 1985) and zoysiagrass (Juska, 1959) had increased root growth in response to increasing N show a significant growth reduction in response to shortmay rates. Root growth in response to N in this research ened photoperiod. Total shoot growth did not differ indicate that root growth increased within the con- between grasses under long-day conditions; under shortgrowth fines of the pots as a response to overall increased shoot day conditions, however, average shoot growth was approximately in response to N. 50% greater in Tifdwarf than in Floraincrease Roots and rhizomes have previously been shown to Dwarf. in response to K in Coastal bermudagrass (Kei- sling et al., 1979), and in Tifton 44 bermudagrass Root Growth (Belesky and Wilkinson, 1983). FloraDwarf bermudagrass had a slight decrease in root growth in response Root growth in FloraDwarf bermudagrass in the longto K under long days. Conversely, Tifdwarf bermuday study increased linearly in response to N and K dagrass had increased root growth in response to K (Table 1; Fig. 2A). Greatest root weights of 10.9 mg under short days. Increased root and rhizome producm wk 1 were obtained with 9.8 g N and 0.6 g K m 2 tion in response to K fertilization has been associated mo 1. Root weights averaged 7.7 mg m 2 wk 1. Root with increased spring regrowth and cold temperature growth of FloraDwarf in the short-day study was not tolerance (Belesky and Wilkinson, 1983; Keisling et al., influenced by N and K across the range of treatments 1979). This may indicate that these grasses have good in this study. Root weights averaged 3.0 mg m 2 wk 1, capacity for enduring cold temperatures and for spring which was a decrease of 61% from root production regrowth when provided with ample K. under long-day conditions. The reduced root growth model for Tifdwarf bermu- Tissue Total Nonstructural Carbohydrate dagrass under long-day conditions included linear and quadratic N and the interaction of N K (Table 1; Fig. Concentration 2B). Greatest root weights of 24.6 mg m 2 wk 1 were Levels of N and K had no effect on TNC concentration obtained with N at 9.8 and K at 4.9 g m 2 mo 1. Average in FloraDwarf under long-day conditions (Table root weights were 17.6 mg m 2 wk 1. Tifdwarf root 1). Average TNC concentration was 15.7 g kg 1. Under weights in the short-day study were influenced by linear short days, the reduced model for TNC concentration N and K as well the quadratic K component (Table 1; in FloraDwarf included N linear and quadratic effects Fig. 2C). Greatest root weights of 19.4 mg m 2 wk 1 (Table 1; Fig. 3A). Predicted maximum TNC level of were produced with 9.8 g N and 4.2 g K m 2 mo g kg 1 was obtained with 5.9 g N m 2 mo 1. Average Average root weights for Tifdwarf under short days TNC concentration was 34.1 g kg 1, which was an inwere 15.4 mg m 2 wk 1, a decrease of 13% from long- crease of 117% over long-days levels. day conditions. Root production averaged 57 and 80% The reduced model for TNC concentration in Tif- greater in Tifdwarf than FloraDwarf under long and dwarf under long days included N linear and quadratic short days, respectively. components (Table 1; Fig. 3B). Maximum predicted Roots of turfgrass do not typically increase in re- concentration of 31.2 g kg 1 was reached with 4.4 g N sponse to N, which is used more preferentially for shoot m 2 mo 1. Average TNC level was 26.3 g kg 1. Under growth (Goss and Law, 1967; Madison, 1962; Menn and short days, the Tifdwarf TNC reduced model included McBee, 1970; Schmidt and Blaser, 1967), although ber- linear and quadratic components of K (Table 1; Fig.

5 172 CROP SCIENCE, VOL. 38, JANUARY FEBRUARY 1998 Fig. 3. Influence of N (g m 2 mo 1 ) and K (g m 2 mo 1 ) on total nonstructural carbohydrate concentration in root tissue during establishment in a sand medium in a glasshouse in consecutive Fig. 4. Influence of N (g m 2 mo 1 ) and K (g m 2 mo 1 ) on quality studies. (A). FloraDwarf bermudagrass short ( 13 h) days. (B). scores during establishment in a sand medium in a glasshouse in Tifdwarf bermudagrass long ( 13 h) days. (C). Tifdwarf bermudays. consecutive studies. (A). FloraDwarf bermudagrass long ( 13 h) dagrass short ( 13 h) days. (B). FloraDwarf bermudagrass short ( 13 h) days. (C). Tif- dwarf bermudagrass long ( 13 h) days. (D). Tifdwarf bermudagrass short ( 13 h) days. 3C). Maximum predicted TNC concentration of 37.2 g kg 1 was reached with 3.0 g K m 2 mo 1. Carbohydrate had previously been observed in centipedegrass in a levels averaged 31.3 g kg 1, which represented an 18% greenhouse study (Walker and Ward, 1974). increase over long-day levels. Greatest average accumulation of TNC occurred in Total nonstructural carbohydrate levels averaged FloraDwarf under short days. Due to slower growth 68% greater in Tifdwarf than in FloraDwarf under long rates of this cultivar, there may be less demand on redays. Conversely, under short days, FloraDwarf had serve energy supplies, resulting in greater accumulation approximately 9% higher TNC levels than did Tifdwarf. of TNC. Additionally, intraspecific differences in degree Previous research on TNC concentration in turfgrass of cold hardening and cold tolerance between Florahas shown different responses to N. An inverse relationto Dwarf and Tifdwarf may account for variability, similar ship has been found between N fertilization and TNC that reported by Miller and Dickens (1996) for Tif- concentration (Adams et al., 1974; Duff, 1974; Hull and dwarf and Tifway. Smith, 1974; Schmidt and Blaser, 1969; Walker and Ward, 1974). Quadratic responses to N indicated that Quality a certain amount of N was used in carbohydrate accumu- The reduced model for quality scores of FloraDwarf lation, but that excessive N fertilization increased shoot bermudagrass under long-day conditions included linear growth and subsequently depleted stored carbohy- and quadratic N and linear K effects (Table 1; Fig. 4A). drates. Highest quality scores of 6.9 were obtained with N at Turfgrass TNC accumulation in response to K is less 9.8 g m 2 mo 1 in combination with K at 0.6 g m 2 mo 1. well documented than response to N. Under short days, A minimally acceptable score of 6.0 for commercial turf turf growth increased in response to K, and TNC levels use was predicted at 5.5 g N and 0.6 g K m 2 mo 1. were subsequently reduced as a result of the increased Under short days, the reduced model for quality of growth in Tifdwarf. Miller and Dickens (1996) found FloraDwarf bermudagrass increased linearly due to an inverse accumulation of root and rhizome TNC levels both N and K (Table 1; Fig. 4B). A score of 6.0 was in Tifdwarf and Tifway in response to K. Tifgreen, how- reached with 6.0 g N and 4.6 g K m 2 mo 1. ever, had no TNC accumulation in response to K (Goat- Under long days, the reduced model for Tifdwarf ley et al., 1994). bermudagrass quality included N linear and quadratic A seasonal influence on TNC accumulation was evi- components (Table 1; Fig. 4C). Maximum predicted dent in both grasses, with higher levels accumulated quality scores of 7.6 were obtained with 8.4 g N m 2 under short days. Increased TNC accumulation from mo 1. A score of 6.0 was predicted with 3.3 g N m 2 September to November has previously been reported mo 1. Under short days, the reduced model for quality (Dunn and Nelson, 1974; Miller and Dickens, 1996) and in Tifdwarf bermudagrass consisted of N linear and K is believed to be associated with cold hardening. Under linear and quadratic effects (Table 1; Fig. 4D). A maxilong days, FloraDwarf did not accumulate TNC. It addi- mum predicted quality score of 7.5 was reached with tionally had low N and K levels, and a greater rate of 9.8 g N and 3.5 g K m 2 mo 1. A score of 6.0 was growth than under short days. These factors indicated obtained at 1.2 g N and 2.1 g K m 2 mo 1. that nutrients were used for growth, which subsequently Tifdwarf bermudagrass quality scores averaged apdepleted TNC stores, resulting in lack of response to proximately 13% higher than FloraDwarf for both studies. this variable. A similar lack of response to N and K Under short day conditions, quality in both grasses

6 TRENHOLM ET AL.: BERMUDAGRASS GROWTH, CARBOHYDRATE CONCENTRATION, AND QUALITY 173 increased quadratically in response to N. Quality scores tages for overwintering of grasses, subsequent spring in previous research have shown both linear and quadratic green-up, and other stress factors. Total root growth in increases in response to N in Tifgreen (Goatley response to N in this research was attributed to overall et al., 1994) and Tifway (Johnson et al., 1987). McCaslin increased growth due to N fertilization. et al. (1989) reported differential linear increases of Greater TNC accumulation in FloraDwarf bermudagrass quality scores in response to N for 10 bermudagrass cultivars. in the fall may result in increased cold temperaquality ture tolerance, as well as earlier spring regrowth and Lack of response to K for bermudagrass quality scores subsequent green-up. This could further result in inhas been previously reported in Tifgreen (Goatley et creased quality scores and greater overall stress tolerance al., 1994) and Tifway (Johnson et al., 1987). Decreased of this grass. quality, however, is not generally associated with re- Nitrogen consistently increased quality ratings in both sponse to K, as observed in FloraDwarf under long-day grasses. Response was greater during summer, when conditions. Conversely, both grasses increased quality growth was increased. Response under long days scores in response to K under short-day conditions. Previously reached a maximum qualitative response to N for all reported qualitative responses to K include in- variables, while responses were linear during short days. creased winter hardiness, earlier spring green up, and Quality responses to K occurred only under short-day improved stress tolerances (Belesky and Wilkinson, conditions, with greater response in Tifdwarf than in 1983; Gilbert and Davis, 1971; Juska and Murray, 1974). FloraDwarf. Average qualitative scores were slightly higher in Tifdwarf than in FloraDwarf. This was due CONCLUSIONS to the more vigorous overall growth habit of Tifdwarf bermudagrass. As noted previously, the more vigorous Results of these studies indicated that shoot and root growth of Tifdwarf bermudagrass may be advantageous growth, TNC concentration, and quality ratings for during establishment; in the long run, however, excess these cultivars during establishment differed due to cultivar, growth of turfgrass is not desirable. photoperiod, and rates of N and K. The photoperi- odic sensitivity of FloraDwarf bermudagrass resulted in ACKNOWLEDGMENTS reduction of growth rates under short-day conditions, The authors gratefully acknowledge the Florida Turfgrass which is an important management consideration for Research Foundation for their partial support of this project establishment or renovation of putting greens. Timing and Dr. Ramon Littell of the University of Florida s IFAS of these practices should allow for growth of FloraDwarf Statistics Dep. for statistical advice. during maximum photoperiods ( 13 h). In establishment during optimal photoperiod, 4.9 g N m 2 mo 1 REFERENCES provided FloraDwarf with 84% of the total growth at- Adams, W.E., A.W. White, R.A. McCreery, and R.N. Dawson tained by Tifdwarf, 58% greater stolon production, and Coastal bermudagrass forage production and chemical composition 24% longer stolons than Tifdwarf (Trenholm et al., as influenced by potassium source, rate, and frequency of applica- 1997). tion. Agron. J. 59: Adams, W.E., P.J. Bryan, and G.E. Walker Effects of cutting Nitrogen at rates up to 9.8 g m 2 mo 1 increased height and nitrogen nutrition on growth pattern of turfgrasses. p. total shoot growth in both grasses. Growth responses In E.C. Roberts (ed.) Proc. 2nd Int. Turfgrass Res. Conf., varied, however, between cultivars and daylengths. Dur- Blacksburg, VA June ASA and CSSA, Madison, WI. ing summer months, total shoot growth rates did not Belesky, D.P., and S.R. Wilkinson Response of Tifton 44 and Coastal bermudagrass to soil ph, potassium, and nitrogen source. differ between grasses, although rate of response to N Agron. J. 75:1 4. was greater in Tifdwarf bermudagrass. During establish- Burton, G.W., J.E. Hook, J.L. Butler, and R.E. Hellwig Effect ment in reduced photoperiods, however, growth of of temperature, daylength, and solar radiation on production of FloraDwarf bermudagrass was significantly less than Coastal bermudagrass. Agron. J. 80: that of Tifdwarf. Greater shoot growth of Tifdwarf berof applying six nitrogen sources on coastal bermudagrass. Agron. Burton, G.W., and J.E. Jackson Effect of rate and frequency mudagrass is beneficial during establishment and should J. 54: result in a more dense turf and faster attainment of Carrow, R.N., B.J. Johnson, and R.E. Burns Thatch and quality acceptable turf quality. After establishment, however, of Tifway bermudagrass in relation to fertility and cultivation. increased shoot growth is not desirable in a turfgrass, Agron. J. 79: Chaparro, C.J., L.E. Sollenberger, and K.H. Quesenberry Light where greater amounts of tissue are removed at each interception, reserve status, and persistence of clipped Mott elemowing event, subsequently subjecting turf to greater phantgrass swards. Crop Sci. 36: stress. Due to interaction by grass and season in reand Christiansen, S., O.C. Ruelke, W.R. Ocumpaugh, K.H. Quesenberry, sponse to K, application of K during establishment J.E. Moore Seasonal yield and quality of Bigalta, Re- might be reduced or managed in conjunction with N dalta, and Floralta limpograss. Trop. Agric. (Trinidad) 65: Cripps, R.W., J.L. Young and A.T. Leonard Effects of potasuntil mid to late summer. Tifdwarf bermudagrass had sium and lime applied for Coastal bermudagrass production on a continual shoot growth response to K during establish- sandy soil. Soil Sci. Soc. Am. J. 53: ment, either as a main effect or as an interaction with Dudeck, A.E., C.H. Peacock, and T.E. Freeman Response of N. Response to K in FloraDwarf bermudagrass was selected bermudagrasses to nitrogen fertilization. p In F. Lemaire (ed.) Proc. 5th Int. Turfgrass Res. Conf., Avignon, France. largely limited to short-day conditions, when growth of 1 5 July. Inst. Natl. de la Recherche Agron., Paris. this grass was most limiting. Dudeck, A.E Bermudagrass plant FHB-135. U.S. Patent Plant Root growth response to K may have greater advan Date issued: 3 Jan

7 174 CROP SCIENCE, VOL. 38, JANUARY FEBRUARY 1998 Duff, D.T Influence of fall nitrogenous fertilization on the and nitrogen treatments of Agrostis palustris Huds. Seaside and carbohydrates of Kentucky bluegrass. p In E.C. Roberts Agrostis tenuis Sibth. Highland on population, yield, rooting, and (ed.) Proc. 2nd Int. Turfgrass Res. Conf., Blacksburg, VA cover. Agron. J. 54: June ASA and CSSA, Madison, WI. Marousky, F.J., A.E. Dudeck, L.B. McCarty, and S.F. Anderson Dunn, J.H., and C.J. Nelson Chemical changes occurring in Influence of daylength and fertility on growth of bermudagrass three bermudagrass turf cultivars in relation to cold hardiness. cultivars. Proc. Fla. State Hortic. Soc. 105: Agron. J. 66: McCaslin, B.D., M.R. Hughes, and A.A. Baltensperger Nitrogen Freund, R.J., and R.C. Littell SAS Systems for regression. 2nd fertilization genotype interactions influence bermudagrass ed. SAS Inst., Cary, NC. turf quality characteristics. J. Am. Soc. Hortic. Sci. 114(1): Fry, J.O., and P.H. Dernoeden Growth of zoysiagrass from Menn, W.G., and G.G. McBee A study of certain nutritional vegetative plugs in response to fertilizers. J. Am. Soc. Hortic. requirements for Tifgreen bermudagrass utilizing a hydroponic Sci. 112: system. Agron. J. 62: Gaussoin, R.E., A.A. Baltensperger, and B.N. Coffey Response Miller, G.L., and R. Dickens Bermudagrass carbohydrate levels of 32 bermudagrass clones to reduced light intensity. Hort- as influenced by potassium fertilization and cultivar. Crop Sci. Science 23(1): : Gilbert, W.B., and D.L. Davis Influence of fertility ratios on Reeves, S.A., Jr., G.G. McBee, and M.E. Bloodworth Effects winter hardiness of bermudagrass. Agron. J. 63: of N, P, and K tissue levels and late fall fertilization on the cold Goatley, J.M., V. Maddox, D.J. Lang, and K.K. Crouse Tifgreen hardiness of Tifgreen bermudagrass (Cynodon dactylon C. transgen bermudagrass response to late-season application of nitro- vaalensis ). Agron. J. 62: and potassium. Agron. J. 86:7 10. SAS Institute SAS user s guide: Statistics. 6th ed. SAS Inst., Goss, R.L., and A.G. Law Performance of bluegrass varieties Cary, NC. at two cutting heights and two nitrogen levels. Agron. J. 59: Schmidt, R.E., and R.E. Blaser Effect of temperature, light, Horst, G.L., L.B. Fenn, and N.B. Dunning Bermudagrass turf and nitrogen on growth and metabolism of Tifgreen bermudagrass responses to nitrogen sources. J. Am. Soc. Hortic. Sci. 110(6): (Cynodon spp.). Crop Sci. 9: Schmidt, R.E., and R.E. Blaser Effect of temperature, light, Hull, R.J., and L.M. Smith Photosynthate translocation and and nitrogen on growth and metabolism of Cohansey bentgrass metabolism in Kentucky bluegrass turf as a function of fertility. p. (Agrostis palustris Huds.). Crop Sci. 7: In E.C. Roberts (ed.) Proc. 2nd Int. Turfgrass Res. Conf., Smith, D Removing and analyzing total nonstructural carbohy- Blacksburg, VA June ASA and CSSA, Madison, WI. drates from plant tissue. Wisconsin Agric. Exp. Stn. Rep. R2107. Johnson, B.J., R.N. Carrow, and R.E. Burns Bermudagrass turf Univ. of Wisconsin, Madison. response to mowing practices and fertilizer. Agron. J. 79: Trenholm, L.E., A.E. Dudeck, J.B. Sartain, and J.L. Cisar Juska, F.V Response of Meyer zoysia to lime and fertilizer Cynodon responses to nitrogen, potassium and daylength during treatments. Agron. J. 51: vegetative establishment. Int. Turfgrass Soc. Res. J. 8: Juska, F.V., and J.J. Murray Performance of bermudagrass in Walker, R.H., and C.Y. Ward Influence of N and K nutrition the transition zone as affected by potassium and nitrogen. p. 149 on net photosynthesis, dark respiration, and carbohydrates in centipedegrass In E.C. Roberts (ed.) Proc. 2nd Int. Turfgrass Res. Conf., p In E.C. Roberts (ed.) 2nd Int. Turfgrass Blacksburg, VA June ASA and CSSA, Madison, WI. Res. Conf., Blacksburg, VA June ASA and CSSA, Keeley, P.E., and R.J. Thullen Influence of planting date on Madison, WI. growth of bermudagrass (Cynodon dactylon ). Weed Sci. 37: White, R.H., and R.E. Schmidt Fall performance and postdormancy growth of Midiron bermudagrass in response to nitro- Keisling, T.C., F.M. Rouquette, Jr., and J.E. Matocha Potassium gen, iron, and benzyladenine. J. Am. Soc. Hortic. Sci. 115(1): fertilization influences on Coastal bermudagrass rhizomes, roots, Wilkinson, S.R., and G.W. Langdale Warm-season grasses. p. and stand. Agron. J. 71: In D.A. Mays (ed.) Forage fertilization. ASA, CSSA, and Madison, J.H Turfgrass ecology. Effects of mowing, irrigation, SSA, Madison, WI.