Tall Fescue Cultivars Research Articles

Nutrient Accumulation and Associated Root Characteristics in Response to Drought Stress in Tall Fescue Cultivars

Drought is a major factor limiting the growth of turfgrasses in many areas. The functional relationship of drought stress and accumulation of various ions in turfgrasses is not well understood. The objective of this study was to investigate the effects of drought on root growth and accumulation of several major nutrients in three tall fescue (Festuca arundinacea Schreb.) cultivars varying in drought tolerance (Falcon II = Houndog V > Rebel Jr). Grasses were grown in well-watered or drying (nonirrigated) soil for 35 days in a greenhouse. Drought conditions limited total root length to a greater extent for `Rebel Jr' than for `Falcon II' and `Houndog V', while specific root length (SRL) was greater in `Falcon II' and `Houndog V' than in `Rebel Jr'. Concentrations of N, P, and Mg decreased, whereas those of K, Ca, and Fe increased, in shoots of drought-stressed plants of all three cultivars. Root N was not affected, but root P decreased in `Rebel Jr', and root K decreased in all three cultivars under drought conditions. Drought reduced the proportions of N and P in shoots and increased those in roots, while increasing the proportion of K in shoots and decreasing that in roots. During drought stress, both `Falcon II' and `Houndog V' maintained higher K concentration in shoots, and `Falcon II' in roots, than did `Rebel Jr', but `Rebel Jr' and `Houndog V' had higher Fe concentration in shoots than did `Falcon II'. The higher K and lower Fe accumulations in shoots could contribute to better drought tolerance of tall fescue cultivars.

Preference by sheep and goats among hay of eight tall fescue cultivars.

Grazing ruminants use both visual cues and taste in selecting their diet. Preference during grazing may not be the same when forage is dried for hay and cut into lengths prior to feeding in confinement. Eight cultivars of tall fescue (Festuca arundinacea Schreb.), previously evaluated for preference while grazed, were harvested three times over a period of 2 yr. The hays were air-dried, baled, and passed through a hydraulic bale processor prior to feeding. Five experiments were conducted. All three harvests were evaluated with sheep and the last two also with goats, using six animals each time. During an adaptation phase, hays were offered alone as meals. In the experimental phase, every possible pair of hays (28 pairs) was presented for a meal. Data were analyzed by multidimensional scaling and by traditional analyses. Preference was significant among cultivars in all experiments. Multidimensional scaling showed that selection was based on two criteria with two dimensions being significant. Sheep preferred KENHY followed by KENTUCKY 31 and STARGRAZER but preferenced against BARCEL. HIMAG, MO-96, and C1 were intermediate and MOZARK was variable. Goats were similar to sheep in preferring KENHY followed by STARGRAZER and selected against MOZARK and BARCEL. KENTUCKY 31, HIMAG, MO-96, and C1 were intermediate. In all five experiments, the general association was positive for available carbohydrate fractions and negative for fiber fractions that contribute to cell wall rigidity.

Nonstructural Carbohydrates in Tall Fescue Cultivars: Relationship to Animal Preference

Grazing animals prefer some plants to others. These choices are likely related to physical and chemical factors such as energy‐dense carbohydrates contained in plants. This study quantified the nonstructural carbohydrate fractions in each of eight vegetatively growing, endophyte‐free, tall fescue cultivars (Festuca arundinacea Schreb.) and relates their sugar concentrations to cattle grazing preferences. The experimental area consisted of eight cultivar plots replicated three times in each of three pastures. Within each pasture, forage was sampled between 0830 and 1000 h mountain daylight time (MDT) during each of four seasons and 2 yr. Freeze‐dried forage samples were extracted with hot water and an amylase (Clarase) solution. Sugars were quantified colorimetrically using potassium‐ferricyanide and glucose‐oxidase methods. Cattle grazing preferences among these tall fescue cultivars were related to the concentrations of total nonstructural carbohydrates (TNC) Other sugar fractions were not significantly related to grazing preference in this study. The nonstructural carbohydrate concentrations averaged over the entire study were glucose, 14; fructose, 5; sucrose, 40; fructan, 23; insoluble starch, 24; and TNC, 129 g kg−1. A forage selection criterion should include measures of the TNC because of their close relationship to animal grazing preference.

Alleviating Tall Fescue Toxicosis Problems with Nontoxic Endophytes

In 1943, a cultivar of tall fescue (Festuca arundinacea) later known as Kentucky 312 was released for sale. This cool season grass became widely distributed in the southeastern United States because it was persistent in the face of drought, grew on poor soils and provided good erosion control, as well as large amounts of forage for hay or grazing.2 By 1950, it was recognized that animals grazing tall fescue did not perform as well as forage analysis would predict.2 In 1977, research (Bacon) revealed the presence of an endophyte, Neotyphodium coenophialum, in the intercellular spaces of the leaf sheath. Later research connected this endophyte with what is now recognized as fescue toxicosis.4,5 With the discovery of the endophyte in tall fescue, the solution to the toxicity problem became obvious: remove the endophyte.1 With endophyte-free fescue, animal performance improved but the plants were not as hardy, and stand loss in endophyte-free fescue became a problem.3

Chitinase Activity in Tall Fescue Seedlings as Affected by Cultivar, Seedling Development, and Ethephon

Recent reports indicate that tall fescue (Festuca arundinacea Schreb.) may be selected for increased disease resistance with the use of a marker such as chitinase, a defense protein associated with disease resistance in tall fescue. The objective of this study was to determine if chitinase activity in tall fescue cultivars differs consistently across seedling stage, and to determine if chitinase activity could be increased with ethephon ([2-chloroethyl]phosphonic acid), a growth regulator used as a chemical elicitor. Ten cultivars of tall fescue were planted in a greenhouse, and seedlings were harvested at 14, 28, and 42 d after germination. Seedlings were treated with and without ethephon 3 d prior to each harvest. Foliage was analyzed for total and specific chitinase activity. Both total and specific chitinase activity differed (P < 0.01) among cultivars and seedling stages. Highest ranking cultivars expressed at least 16% more total chitinase activity and 18% more specific activity than the lowest ranking cultivars. Though chitinase activity changed drastically over seedling development, there were no cultivar × seedling stage interactions (P < 0.01) for total or specific activity. Ethephon increased total and specific activity only at the 0.06 and 0.07 probability level and was far less effective than biological elicitors used to increase chitinase in previous studies. We concluded that chitinase could serve as a consistent marker among tall fescue cultivars across seedling stages, but a more effective chemical elicitor would be desirable to increase chitinase activity.

Malate, Citrate, and Amino Acids in Tall Fescue Cultivars: Relationship to Animal Preference

Grazing animals depend on little‐understood chemical and physical cues when selecting forage diets. This study determined malate, citrate, and amino acid concentrations in endophyte‐free tall fescue (Festuca arundinacea Schreb.) and related those concentrations to cultivar, harvest time, and grazing‐animal preference. ‘Barcel’, ‘Kenhy’, ‘Kentucky‐31’, ‘Missouri‐96’, ‘Mozark’, ‘Stargrazer’, and the two accessions C1 and HiMag were established in three replicates within each of three pastures. Organic acids were determined on regrowth within each plot during four seasons and two years; amino acids were determined on regrowth of four cultivars across three replicates during both spring and fall seasons in one year. Malate and citrate were extracted with boiling water and quantified by high‐performance liquid chromatography (HPLC) with an organic acid column. Amino acids were hydrolyzed, separated by ion‐exchange HPLC, and quantified as their ninhydrin derivatives. Both malate and citrate concentrations differed between years. During one year only, malate concentrations were higher in Kenhy (68 g kg−1 dry matter [DM], most preferred) than in Mozark (54 g kg−1 DM, least preferred). Citrate concentrations (13 g kg−1 DM) were not different among cultivars. Eighteen amino acids (including tryptophan) accounted for 75% of total N. Thus, tissue N data were used as covariates to amino acid data in the ANOVA. Kenhy contained higher concentrations of eight amino acids than did other cultivars. These differences may reflect presence of Lolium genes in Kenhy. Cattle (Bos taurus L.) grazing preference (0 = not eaten; 10 = completely eaten) was not related to malate, citrate, or amino acid concentrations among cultivars.

Morphological and physiological effects of water deficit and endophyte infection on contrasting tall fescue cultivars

Morphological and physiological responses to water deficit of two tall fescue (Festuca arundinacea) cultivars were compared in a glasshouse experiment and the effect, on those responses, of artificial infection of the tall fescue plants with two fungal endophyte (Neotyphodium coenophialum) strains was evaluated. The cultivars were Maris Kasba (MK), of Mediterranean origin, and El Palenque (EP), an Argentinian cultivar of temperate origin. The endophyte strains AgResearch isolate (AR501) and the Kentucky (KY31) wild type were compared with nil‐endophyte controls. Leaf growth rate of EP plants under water deficit was higher and leaf senescence rate lower than for MK plants (P < 0.05). MK plants showed a greater increase in the proportion of dead leaf tissue than EP plants as water deficit increased (P < 0.05). Stomatal conductance and lamina osmotic adjustment at low soil moisture were lower for MK than EP (P < 0.05). Endophyte‐infected plants had a lower dry weight and tiller number, but a higher net growth rate during water deficit treatments than endophyte‐free plants (P < 0.05). A significant cultivar × endophyte interaction (P < 0.05) was observed for many variables studied. This implies that any new endophyte strain should be evaluated in combination with the plant genotypes with which it is likely to be associated in commercial practice. MK‐KY31 and EP‐AR501 associations appeared to tolerate short‐term water deficit more effectively than other associations studied. There was evidence that the two endophyte strains studied had different physiological effects on their tall fescue host plants.

Malate, Citrate, and Amino Acids in Tall Fescue Cultivars

Malate, Citrate, and Amino Acids in Tall Fescue Cultivars

Root Physiological Characteristics Associated with Drought Resistance in Tall Fescue Cultivars

Knowledge of root traits associated with drought tolerance is important for further understanding drought tolerance mechanisms of the whole plant. The experiment was designed to investigate effects of drought stress on root physiological activities of six cultivars (Kentucky‐31, Falcon II, Houndog V, Phoenix, Rebel Jr., and Bonsai) of tall fescue (Festuca arundinacea Schreb.) varying in drought resistance. Grasses were grown in well‐watered or drying (nonirrigated) soil for 35 d in a greenhouse. Drying reduced root length and dry mass in the 0‐ to 20‐cm layer for all six cultivars. Root length and dry mass in the 40‐ to 60‐cm layer was enhanced for Houndog V, Falcon II, and Kentucky‐31; was not affected for Phoenix and Bonsai; and was reduced for Rebel Jr. by soil drying. Water uptake rates for Falcon II and Kentucky‐31 decreased with soil drying in the 0‐ to 20‐cm layer but increased in the 40‐ to 60‐cm layer. Soil drying limited water uptake by Rebel Jr. in both layers. Drought stress increased root mortality in the 0‐ to 20‐, 20‐ to 40‐, and 40‐ to 60‐cm layers, but the increase was most dramatic in the surface soil layer. The increase in root mortality in each soil layer was most severe for Rebel Jr. and least severe for Kentucky‐31. Root death of tall fescue cultivars during drought was positively correlated with root desiccation, as evidenced by severe leakage of organic solutes from roots in drying soil. Carbohydrate supply to roots was not a contributor to root death during drought stress. This was supported by the increased or unaffected total nonstructural carbohydrates in both shoots and roots, and the increased C allocation to roots under soil drying conditions.

Top Growth and Rooting Responses of Tall Fescue Cultivars Grown in Hydroponics

Use of turf‐type tall fescue (Festuca arundinacea Schreb.) as a reduced‐input and drought‐resistant turfgrass species has increased in recent years. Several growth types of tall fescue have been identified. Concerns have been expressed about the rooting responses of cultivars classified as turf type and dwarf type. Turf‐ and dwarf‐type tall fescues may lack the potential drought‐avoidance characteristics associated with cultivars like Kentucky 31. This study was conducted in hydroponics under greenhouse conditions to determine whether potential differences in top and root growth responses exist among tall fescue cultivars, experimental lines, and growth types. Sixteen cultivars and experimental lines, representing four growth types (i.e., dwarf, turf, intermediate, and forage) were evaluated. Tall fescue cultivars, experimental lines, and growth types differed in top growth and rooting responses. All cultivars and lines, except ‘Jaguar’ and ‘Kenhy’, produced roots to the 600‐ to 750‐mm sampling depth. Dwarf‐ and turf‐type cultivars and lines had the best responses for total root production and distribution under the conditions of this study. ‘Silverado’, ‘Eldorado’, ‘Trailblazer’, and 516 had relatively high verdure yields ranging from 5.3 to 5.7 g, low clipping yields ranging from 3.6 to 3.9 g, and a clipping yield to verdure ratio (CY/V) of 0.7. Results from this study refute concerns expressed by some persons in the turfgrass industry regarding the potential for reduced depth and extent of rooting in dwarf‐ and turf‐type tall fescues. These data further support the presence of genotypes with abilities to express deep, extensive root systems and favorable characteristics for drought avoidance potential.

Population Differentiation, Spatial Variation, and Sampling of Tall Fescue under Grazing

Tall fescue [Festuca arundinacea Schreb.] is the most important cool‐season perennial forage grass in Alabama and the southeastern USA. Genetic variation is essential for breeding improved cultivars, and understanding factors influencing genetic variability in pastures is important if material from existing pastures is to be used in a breeding program. This study was conducted to determine the extent of differentiation for agronomic traits in pastures grazed long‐term and to investigate possible spatial variation and its effect on sampling. Three populations from permanent pasture treatments of the USDA SARE cropping system trial in Virginia were sampled: (i) pure tall fescue fertilized with N, stocked continuously (Fescue + N); (ii) tall fescue–alfalfa (Medicago sativa L.) mixture used as hay and pasture (Fescue + alfalfa); and (iii) tall fescue–red clover (Trifolium pratense L.) mixture used as hay and pasture (Fescue + red clover). The tall fescue cultivar was endophyte‐free Ky 31 [fescue endophyte: Neotyphodium coenophialum; syn. Acremonium coenophialum]. Plants from these paddocks were established in central Alabama in 1995. Original seed from the SARE trial were also germinated for establishing the original population. Ex situ evaluation was conducted in Alabama (1995–1997). Compared with plants derived from the original seed lot, plants derived from pastures under grazing had significantly earlier maturity, higher dry matter (DM) yield per plant, and larger plant diameter, indicating population differentiation in response to grazing. No significant differences were observed among populations with different pasture management treatments. Statistical and graphical analysis of spatial variation of agronomic traits showed no spatial relationships in any of the six sampled paddocks. Bootstrap estimates of minimum and maximum values indicated that 25 individuals per paddock captured most of the phenotypic variation within each paddock. A random walk approach covering the entire unit being sampled seems therefore to be an appropriate strategy for sampling similar pastures to obtain base material for a breeding program.

Physiological Responses of Diverse Tall Fescue Cultivars to Drought Stress

Drought is among the most limiting factors for turfgrass growth. Understanding genetic variations and physiological mechanisms in turfgrass drought resistance would facilitate breeding and management programs to improve drought resistance. The experiment was designed to investigate shoot physiological responses of six tall fescue (Festuca arundinacea Schreb.) cultivars representing several generations of turfgrass improvement to drought stress. Grasses were grown in well-watered or drying (nonirrigated) soil for 35 days in the greenhouse. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), relative water content (RWC), and photochemical efficiency (Fv/Fm) declined during drought progression in all cultivars, but the time and the severity of reductions varied with cultivar and physiological factors. The values of Pn, RWC, gs, and Tr decreased significantly for `Rebel Jr', `Bonsai', and `Phoenix' when soil water content declined to 20% after 9 days of treatment (DOT) and for `Houndog V', `Kentucky-31', and `Falcon II' when soil water content dropped to 10% at 15 DOT. A significant decrease in Fv/Fm was not observed in drought-stressed plants until 21 DOT for `Rebel Jr', `Bonsai', and `Phoenix' and 28 DOT for `Houndog V', `Kentucky-31', and `Falcon II'. The decline in Pn resulted mainly from internal water deficit and stomatal closure under mild drought-stress conditions. After a prolonged period of drought stress (35 DOT), `Falcon II', `Houndog V', and `Kentucky-31' maintained higher Pn than did `Rebel Jr', `Bonsai', and `Phoenix', which could be attributed to their higher Fv/Fm. This study demonstrated variation in drought resistance among tall fescue cultivars, which was related to their differential responses in photosynthetic capacity and water relations.

278 Gas Exchange and Water Relations of Diverse Tall Fescue Cultivars in Response to Drought Stress

To investigate shoot physiological responses to drought stress of six tall fescue (Festuca arundinacea) cultivars representing several generations of turfgrass improvement, forage-type `Kentucky-31', turf-type `Phoenix', `Phoenix', and `Houndog V', and dwarf-type `Rebel Jr` and `Bonsai' were grown in well-watered or drying soil for 35 days in a greenhouse. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), relative water content (RWC), and photochemical efficiency (Fv/Fm) declined during drought progression in all cultivars, but the time and the severity of reductions varied with cultivars and physiological factors. Pn, RWC, gs, and Tr decreased significantly for `Rebel Jr', `Bonsai', and `Phoenix' when soil water content declined to 20% after 9 days of treatment (DOT) and for `Falcon II', `Houndog V', and `Kentucky-31' when soil water content dropped to 10% at 15 DOT. A significant decrease in Fv/Fm was not observed in drought-stressed plants until 21 DOT for `Rebel Jr', `Bonsai', and `Phoenix' and 28 DOT for `Houndog V', `Kentucky-31', and `Falcon II'. The decline in Pn was due mostly to internal water deficit and stomatal closure under short-term or mild drought-stress conditions. After a prolonged period of drought (35 DOT), higher Pn in `Falcon II', `Houndog V', and `Kentucky-31' could be attributed to their higher Fv/Fm.

Integrated effects of host resistance and fungicide concentration on the progress of Rhizoctonia blight in tall fescue turf

Efficacy of the fungicide flutolanil was assessed for control of Rhizoctonia blight, caused by Rhizoctonia solani Kühn, on monostands and blends of two tall fescue ( Festuca arundinacea Schreb.) cultivars. The cultivars Kentucky 31 (moderately resistant to R. solani) and Mojave (susceptible) were seeded in six treatments of ratios between 100 : 0 and 0 : 100 of each cultivar, respectively. The monostands and blends were raised to maturity and treated with six rates of flutolanil ranging from 3.4 to 1.1 kg a.i. ha -1. An increase in the proportion of Kentucky 31 in a blend, and application rate of flutolanil acted additively to significantly ( P⩽0.05) suppress the progress of Rhizoctonia blight. Incorporation of Kentucky 31 in all blends, however, failed to limit disease to acceptable levels (<10%) when less than a label rate of fungicide was applied. Greater levels of Rhizoctonia resistance must be identified and incorporated into tall fescue cultivars before host resistance can be used to limit fungicide applications.

Occurrence of the fungal endophyte Neotyphodium coenophialum in leaf blades of tall fescue and implications for stock health

Leaf blades of tall fescue (Festuca arundinaced) plants infected with the endophytic fungus Neotyphodium coenophialum (= Acre‐monium coenophialum) have often been assumed to be endophyte‐free. However, fungal colonies identified as N. coenophialum developed following incubation of surface‐sterilised leaf blades from endophyte‐infected tall fescues on antibiotic potato dextrose agar. A standardised fungal isolation technique was developed to assess the distribution of hyphae within tall fescue leaf blades in three USA‐bred cultivars ('Georgia 5’, ‘Kentucky 31’, ‘Jesup') and a roadside population (MRSP) from the Manawatu region, New Zealand. Leaf blades of the three USA‐bred cultivars were typically sparsely colonised. In contrast, extensively colonised leaf blades were present in many MRSP plants, particularly in autumn. Ergovaline concentrations of up to 3.9 ppm (mean 2.5) were present in leaf blades of the MRSP grown in a glasshouse. Ergovaline at lower concentrations (mean 0.4 ppm) was also detected in leaf blades of the tall fescue cultivars infected with their natural endophytes. These unusually high concentrations of hyphae and ergovaline observed within leaf blades of the MRSP provide an explanation of why fescue toxicosis has been especially severe in New Zealand. Significantly, N coenophialum from plants of the MRSP was not uniform in cultural characteristics and conidial length, or in the ability to colonise leaf blades and produce ergovaline in artificially infected plants of four diverse tall fescue cultivars. The four inoculated cultivars ('Georgia 5’, ‘Grasslands Roa’, ‘Kentucky 31’, ‘KFa949') also differed in their interaction with N. coenophialum from MRSP. The most colonised leaf blades were in plants from an experimental cultivar of Mediterranean origin (KFa949), and, surprisingly, ergovaline concentrations were higher in the leaf blades than sheath. The New Zealand‐bred tall fescue cultivar ‘Grasslands Roa’ was also distinctive in that no hyphae were detected in leaf blades. The concentration of ergovaline present in pooled leaf blades of ‘Grasslands Roa’ plants was lower than in those of the other naturally and artificially infected tall fescue/N. coenophialum populations examined in this study, reflecting the apparently low concentrations of hyphae present.

Use of an Experimental High-Magnesium Tall Fescue to Reduce Grass Tetany in Cattle

Grass tetany (hypomagnesemia) continues to be a problem for the livestock industry. An experimental cultivar of tall fescue (Festuca arundinacea Shreb.) selected for high Mg concentration, HiMag, was compared against four other cultivars for its ability to increase serum-Mg and reduce the risk of grass tetany. Forage from HiMag contained 22% more Mg, 18.5% more Ca, and 9% more P than other cultivars; K levels were not different. Regardless of cultivar, concentrations of Ca and Mg were lower while K and P were higher during the spring than the autumn. The tetany ratio [K/(Ca + Mg) on M c basis] was lower for HiMag than for other cultivars (1.34 vs. 1.65); all cultivars had a higher ratio during spring than autumn (1.91 vs. 1.31). In cattle (Bos taurus) grazing trials, blood serum from steers grazing HiMag contained 8% more Mg in autumn 1993 but was not different in spring 1994. Blood serum Mg was not different for cows (either dry or nursing calves) during autumn grazing, but approached significance (P = 0.09) during the spring 1995 calving season (2.32 vs. 2.07 mg/dL for HiMag vs.other cultivars). Except for differences between calves on HiMag compared with Kentucky-31 in autumn 1995 (58 vs. 43 Ib, respectively), animal weight change was not affected by cultivar. Normal forage Mg concentrations (>0.20%) and tetany ratios below 2.2 for all cultivars in every season except spring 1995 may explain the lack of consistent animal response. No clinical symptoms of grass tetany were observed at any time during these studies. However, the higher Mg concentration and lower tetany ratio suggest that HiMag could provide a means of reducing the incidence of grass tetany in livestock during periods when risk of the disorder is high.

Evaluation of Stenotrophomonas maltophilia strain C3 for biocontrol of brown patch disease

Bacterial strains isolated from grass foliage were tested for inhibition of brown patch disease, caused by Rhizoctonia solani Kühn, on detached blades and potted seedlings of tall fescue ( Festuca arundinacea Schreb. cv. Kentucky 31). Stenotrophomonas maltophilia strain C3 prevented growth of the fungus on leaf blades and reduced the severity of necrosis on seedlings. When strain C3 was tested on tall fescue cv. ‘Kentucky 31’ planted at three seeding densities, biological control was not achieved. When the strain was applied to field plots of six tall fescue cultivars, the severity of brown patch disease was reduced in one cultivar, but increased in another. A rifampicin-resistant mutant strain of C3 applied to four cultivars was recovered from all of the canopies at approximately 10 6 CFU/g foliage throughout the experiment. This population level is over 10-fold lower than that associated with effective antagonism under laboratory conditions.

Water Relations and Canopy Characteristics of Tall Fescue Cultivars during and after Drought Stress

Understanding factors associated with drought resistance and recovery from drought stress in tall fescue (Festuca arundinaces Schreb.) is important for developing resistant cultivars and effective management strategies. Our objective was to investigate water relations, photosynthetic efficiency, and canopy characteristics of tall fescue cultivars (forage-type `Kentucky-31', turf-type `Mustang', and dwarf-type `MIC18') in responses to drought stress and subsequent recovery in the field and greenhouse. During drought stress under field conditions, `MIC18' had lower turf quality, more severe leaf wilting, and higher canopy temperature than `Mustang' and `Kentucky-31', indicating that `MIC18' was more drought-sensitive. The greenhouse study comparing `K-31' and `MIC18' showed that leaf water status, chlorophyll fluorescence, canopy green leaf biomass, and lead area index of both cultivars declined as soil dried. Reductions in relative water content, leaf water potential, chlorophyll fluorescence, canopy green leaf biomass, and leaf area index were more severe and occurred sooner during dry down for `MIC18' than for `Kentucky-31'. After rewatering following 14 days of stress, leaf water deficit and turf growth recovered, to a greater degree for `Kentucky-31' than for `MIC18'. However, soil drying for 21 days caused long-term negative effects on leaf photosynthetic efficiency and canopy characteristics for both cultivars.

Management Studies on Seed Production of Turf‐Type Tall Fescue: I. Seed Yield

AbstractTall fescue (Festuca arundinacea Schreber) is rapidly gaining popularity as a turfgrass. Limited information is available on seed yield response of turf‐type cultivars to seed production management practices. We tested effects of four management variables on seed yield of Bonanza (late‐maturing turf type), Rebel (mid‐maturing turf type), Falcon (early‐maturing turf type), and Fawn (forage type) tall fescue cultivars. Variables were spring‐applied N rates (100, 145, and 190 kg ha−1), N application timing (double‐ridge stage, spikelet initiation, and equally split between the two), row spacing (0.3 and 0.6 m), and post‐harvest residue managements after removing the straw (flailchopping or burning the stubble). Seed yields of the second through fifth crops were measured. Nitrogen application timing did not affect seed yield of any cultivar. Effects of the other three variables on seed yield interacted with each other. For both Fawn and Rebel, high seed yields were achieved when 100 kg N ha−1 was applied and residue was burned, irrespective of row spacing. Bonanza produced high seed yields with 145 kg N ha−1, 0.6‐m row spacing, and flail‐chopping. In contrast, 0.3‐m row spacing and residue burning was required for maximum seed yield in Falcon, whereas N rates did not have an effect. We conclude that seed yield responses of Fawn and Rebel to management practices are similar. Results further suggest that, compared with Fawn, the optimum spring N rate was higher for Bonanza seed production, and the optimum row spacing was narrower for Falcon seed production. Also, residue burning was needed for maintaining high seed yield in Fawn, Rebel, and Falcon, whereas, at optimum row spacing and N rate, mechanical removal of post‐harvest residue was as effective as burning for Bonanza seed production.

Management Studies on Seed Production of Turf‐Type Tall Fescue: II. Seed Yield Components

AbstractInformation on how management affects seed yield components of turf‐type tall fescue (Festuca arundinacea Schreber) cultivars is needed to improve cultural practices for seed production. We tested factorial combinations of two post‐harvest residue managements (flailchopping or burning the stubble), two row spacing (0.3 and 0.6 m), three spring‐applied N rates (100, 145, and 190 kg ha−1), and three N application timings (double‐ridge, spikelet initiation, and equally split between the two) on seed yield components of turf‐type cultivars Falcon, Rebel, and Bonanza, and the forage cultivar Fawn. Seed yields of all cultivars were closely correlated with the number of seeds produced per unit area (m2), but yields were weakly and negatively correlated with weight per seed. Compared with flail‐chopping, burning the residue increased the numbers of fertile tillers, floret sites, and seeds per unit area in all cultivars. The number of seeds per unit area was not affected by row spacing in Fawn and Bonanza, but was increased at 0.3‐m row spacing in Falcon when the residue was burned, and was greater at 0.6‐m in Rebel when the residue was flail‐chopped. Increasing N rate above 100 kg ha‐1 decreased floret site utilization and seeds per unit area in Fawn, but did not affect these components in Falcon and Rebel. Seeds per unit area in Bonanza was the greatest at 145 kg N ha‐1. For all cultivars, N application timing had little effect on seeds per unit area. We conclude that management practices for the turf‐type cultivars should focus on maintaining a high number of fertile tillers throughout the stand life by burning post‐harvest residue. Using narrower row spacings for early‐ and mid‐maturing turf‐type cultivars also could increase the number of fertile tillers per unit area when the post‐harvest residue is burned. The optimum spring‐applied N rate for seed production is apparently greater for the late‐maturing turf types than for forage cultivars.