ential responses to N and K fertilization rates. Liberal N fertilization has increased shoot growth in numerous Hybrid bermudagrass cultivars (Cynodon dactylon L. ؋ C. transbermudagrass cultivars (Burton and Jackson, 1962; Wilvaalensis Burtt-Davy) differ in their responses to N and K for growth, 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-(Ͼ13 h) and short-day (Ͻ13 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 g m Ϫ2 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 Ϫ2 yr Ϫ1 increased each photoperiod was a randomized complete block with factorial root or rhizome weights in 'Coastal' bermudagrass (Keitreatments consisting of two cultivars, four rates of N, four rates sling et al., 1979). Shoot growth in Coastal increased of K, and four replications. Data were analyzed by fitting multiple with up to 14.0 g K m Ϫ2 (Belesky and Wilkinson, 1983) regression equations starting with a second order polynomial model. Growth of FloraDwarf was highly responsive to photoperiod, in that and up to 41.9 g m Ϫ2 (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 K m Ϫ2 (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 Ϫ2 yr Ϫ1 (Johnson et al., reduced TNC levels in FloraDwarf under short days and in Tifdwarf 1987) and promoted early spring green up in 'Tifgreen' under long days, while K fertilization reduced TNC levels in Tifdwarf (Reeves et al., 1970). Potassium fertilization has inunder short days. Quality scores in both cultivars increased in response creased resistance to cultural stresses such as wear, soil to N under long days, and in response to both N and K under short compaction, and cold temperatures (Carrow et al., 1987; days. Results of these studies indicated that growth, TNC accumulation, and quality differed due to cultivar, photoperiod, and rates of Juska and Murray, 1974). N and K.

Increased need for salt tolerant turfgrasses continues due to increased restrictions on water resources and to salt water intrusion into ground water. This is especially critical along coastal areas. Bermudagrass (Cynodon spp.) cultivars are widely used throughout the South on golf courses, home lawns, and sports turf facilities. Information on tolerance of warm‐season turfgrass cultivars to salinity is limited. The purpose of these studies was to document the glasshouse response of eight bermudagrass cultivars to solution cultures differentially salinized with NaCl. Salt was added to a basic nutrient solution to provide five initial salinity levels ranging from 2.7 to 9.9 dS m−1, but no cultivar differences were found in duplicate studies. Overall, top growth decreased 22%, but root growth increased 270% at the highest salt level. When salt levels ranged from 2.4 to 32.5 dS m−1 in a third study, cultivars differed in their response. ‘Tifdwarf’ and ‘Tifgreen’ were most tolerant while ‘common’ and ‘Ormond’ were most sensitive. Based on regression analyses within cultivars, Na increased and K decreased while total Na plus K in top growth was unaffected by salt concentration. Tissue levels of total Na plus K differed among cultivars.

Increased need for salt tolerant grasses continues due to increased restrictions on limited water resources and to salt water intrusion into groundwater. Seashore paspalum (Paspalum vaginatum Swartz.) is used in Australia as a salt tolerant turfgrass, and cultivars are commercially available in the USA. The purpose of this investigation was to document the glasshouse response of four Seashore paspalum turfgrasses to solution cultures differentially salinized with synthetic sea water. A sea salt mixture was added to half‐strength Hoagland's number 2 nutrient solution to provide six salinity treatments ranging from 0.9 to 39.7 dS m−1. A split‐plot design with five replications was utilized to study salinity as the main plot effect and grass as the sub‐plot effect. Turfgrasses differed markedly in salt tolerance. Based on inverse regression analyses, the most salt tolerant experimental selection was FSP‐1 with 50% of its top growth reduced at 28.6 dS m−1; FSP‐2 and ‘Futurf’ were intermediate in salt tolerance with 50% top growth reductions at 21.9 dS m−1; whereas ‘Adalayd’ (‘Excaliber’) was the most sensitive cultivar with 50% top growth reduction at 18.4 dS m−1. The FSP‐1 selection was 3.1 times more salt tolerant than the other grasses when top growth was reduced only 5% at low salt concentrations. Salinity differentially affected tissue content of Ca, C1, K, Mg, and Na between grasses but had no affect on N which averaged 37.3 g kg−1. Maximum tissue content of 22.3 g kg−1 of CI and 16.4 g kg−1 of Na were at a salt concentration of 31 dS m−1 in FSP‐1. However, concentrations of Cl and Na in the other grasses increased linearly 0.4 and 0.5 g kg−1, respectively, with each increase in salinity concentration. Maximum accumulation in this group was at the highest salt treatment of 39.7 dS m−1 where Cl varied between grasses from 24 to 31 g kg−1 and Na varied from 20 to 24 g kg1. Tissue content of Ca, K, and Mg decreased with increased salinity and differed between grasses. No mortality was observed although top growth of all grasses was severely reduced at the highest salt level.

Duplicate studies were conducted to determine salt tolerance during germination of eight bentgrass (Agrostis spp.) cultivars commonly used for overseeding warm-season turf species, such as bermudagrass (Cynodon spp.) putting surfaces. Bentgrass seeds were germinated on agar salinized with 0, 4000, 8000, 12,000, or 16,000 mg·liter-1, with the highest rate approaching one-half seawater salinity. Total germination decreased linearly or quadratically for specific cultivars as salinity increased. Time necessary to reach 50% germination across all salt concentrations was shortest for `Highland' colonial (Agrostis tenuis Sibth) and `Seaside' creeping (A. palustris Huds.) bentgrass (≈3.7 days); intermediate for `Kingstown' velvet (A. canina L.) and `Streaker' red top (A. alba L.) bentgrass (≈4.5 days); and longest for `Penneagle' creeping, `Penncross' creeping, `Exeter' colonial, and `Pennlinks' creeping bentgrass (≈5.3 days). Salt concentrations necessary to reduce germination to 90%, 75%, and 50% indicated that `Streaker' red top and `Seaside' creeping bentgrass were the most salt-tolerant cultivars. `Kingstown' velvet, `Exeter' colonial, and `Highland' colonial bentgrass were intermediate, while `Pennlinks', `Penncross', and `Penneagle' creeping bentgrass were the most salt-sensitive cultivars.

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