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- Author or Editor: R. C. Shearman x
Abstract
Twenty well-watered Kentucky bluegrass (Poa pratensis L.) cultivars were evaluated for evapotranspiration (ET) under controlled environment, using the water-balance method. ET ranged from a low of 3.86 mm·day−1 for ‘Enoble’ to a high of 6.43 mm·day−1 for ‘Merton’, ‘Birka’, and ‘Sydsport’. Cultivars differed in shoot density, verdure, root density, stomatal density, and stomatal index. Only verdure was significantly correlated (r = 0.60) to ET for the 20 cultivars. Five cultivars were selected using cluster analysis to represent categories of high, medium, and low ET rates. ET for these cultivars increased from 1.1- to 1.7-fold when temperature was increased from 25° to 35°C, depending on cultivar. ET at 35° was positively correlated to vertical elongation rate (r = 0.96), and negatively correlated to shoot density (r = − 0.87) and verdure (r = − 0.83) under well-watered conditions.
Abstract
In a 1983 study, ethofumesate at 1.1, 2.2, and 3.3 kg°ha−1; bensulide at kg°ha−1; and an untreated control were compared for annual bluegrass [Poa annua var. annua (L.) Timm] control and injury to ‘Park’ and ‘Touchdown’ Kentucky bluegrass (Poa pratensis L.). Ethofumesate at 1.1 to 3.3 kg°ha−1 reduced verdure and clipping yields of both cultivars, but gave significant P. annua control. Bensulide at 13.6 kg°ha−1 caused no injury and had unsatisfactory P. annua control. In 1984 ethofumesate was applied to ‘Touchdown’ at 1.1 and 2.2 kg°ha−1 and in repeat treatments of 1.1 + 1.1 kg°ha−1 and 2.2 + 1.1 kg°ha−1 with a 30-day interval between treatments, and was compared to bensulide at 13.6 kg°ha−1 and an untreated control. Ethofumesate caused injury at 7 and 15 days after treatment (DAT), but only the repeat treatments had significant injury at 60 DAT. No injury was detectable at 260 DAT. Excellent annual bluegrass control was obtained at 2.2 kg°ha−1 and 2.2 + 1.1 kg°ha−1. Good annual bluegrass reduction was noted for the other treatments with exception of bensulide, which only reduced the pest population by 50%. Lateral spread of ‘Touchdown’ increased with ethofumesate treatment (when compared to the untreated control) due to reduced annual bluegrass competition. Chemical names used: (±)-2-ethoxy-2,3-dihydro-3.3-dimethyl-5-benzofuranyl methanesulfonate (ethofumesate); and O,O-bis(l-methylethyl)S-[2[(phenylsufonyl) aminojethyl] phosphorodithioate (bensulide).
Abstract
Twelve perennial ryegrass (Lolium perenne L.) cultivars were evaluated for evapotranspiration (ET) rates in a field study, using mini-lysimeters placed in a turf area with 150 m fetch. Cultivars differed in ET, verdure, vertical elongation rate (VER), and root density. Evapotranspiration ranged from a low of 4.93 mm·day-1 for ‘Prelude’ on 3 Sept. 1987 to a high of 9.98 mm·day-1 for ‘Linn’ on 13 May 1988. ‘Linn’ had a mean VER that was twice that of ‘Prelude’. VER was positively correlated (r = 0.93) and verdure was negatively correlated (r = −0.89) with ET. Crop coefficients (Kc) ranged from 0.81 to 1.03. ‘Linn’ had a Kc > 1 on five of the six dates tested.
Abstract
This field study was conducted to evaluate soil compaction stress effects on 20 Kentucky bluegrass (Poa pratensis L.) cultivars. Compaction stress reduced lateral spread of most cultivars with none having greater spread in compacted than in non-compacted soil. ‘Vantage’, ‘Cheri’, and ‘Merion’ maintained the same lateral growth under both conditions. Compaction increased stem rust (Puccinia graminis Pers.) incidence, particularly for stem rust susceptible and moderately susceptible cultivars.
A simple marker technique called sequence-related amplified polymorphism (SRAP) provides a useful tool for estimation of genetic diversity and phenetic relationships in natural and domesticated populations. Previous studies and our initial screen showed SRAP is highly polymorphic and more informative when compared to AFLP, RAPD and SSR markers. In this study, applicability of the SRAP markers to obtain an overview of genetic diversity and phenetic relationships present among cool-season (C3) and warm-season (C4) turfgrass species and their relationship with other Gramineae species were tested. Phenetic trees based on genetic similarities (UPGMA, N-J) were consistent with known taxonomic relationships. In some cases, well-supported relationships as well as evidence by genetic reticulation could be inferred. There was widespread genetic variation among C3 and C4 turfgrass species. In Dice based cophenetic matrix, genetic similarities among all species studied ranged from 0.08 to 0.94, whereas in Jaccard based cophenetic matrix, genetic similarities ranged from 0.05 to 0.85. C3 and C4 species were clearly distinguishable and a close relationship between italian ryegrass and tall fescue were obtained based on SRAP. Genome structures of turfgrasses are comparable to other Gramineae species. This research indicates that the SRAP markers are useful for estimating genetic relationships in a wide range of turfgrass species. The SRAP markers identified in this study can provide a useful reference for future turfgrass breeding efforts.
Abstract
Urea frequently is applied to turfs in liquid formulation at low water application rates which enhance potential foliar N uptake. This study was conducted to evaluate foliar N uptake by several cool-season turfgrasses treated with urea applied at low water volume (35 ml · m−2). Urea was applied foliarly to 8 turfgrasses at 2.5 g N m−2 in 35 ml m−2 of water. Verdure was harvested prior to treatment and after treatment at 24, 48, and 72 hr. Total N-uptake increases were primarily a response to increased the percentage of N, since dry matter production was stable for each turfgrass throughout the 72 hr. Maximum N-uptake occurred 24 hr after treatment. Any significant decrease in N-uptake over time suggested N-movement out of the sampling zone. Turfgrass species and cultivars showed differences in total N-uptake which resulted from initial variations in dry matter, percentage of tissue N, and variations in N-uptake rate. The percentage of N recoveries ranged from 31% to 61% for ‘Park’ Kentucky bluegrass and ‘Highlight’ chewings fescue, respectively. Cultivar differences indicated that ‘Baron’ Kentucky bluegrass was more efficient in relation to foliar N-uptake than ‘Park’ Kentucky bluegrass.
Abstract
This study was conducted on ‘Park’ Kentucky bluegrass (Poa pratensis L.) established on a Sharpsburg silty clay loam (Typic Argiudoll). Urea was applied at 0, 0.8, 1.6, 2.4, and 3.2 g N/m2 in 35 ml·m–2 of distilled water. Treatments were applied at 3-week intervals beginning 29 Apr. 1980 and ending 2 Sept. 1980. Turfgrass color, quality, clipping yield, total N percentage in clippings, and tissue succulence were highest for 3.2 g N/m2. Maximum N-rate responses occurred during spring and fall and were highest 1 week after treatment. Acceptable turfgrass quality was maintained at 1.6 g N/m2 per application. Nitrogen recoveries based on clipping removal were 49%, 60%, 59%, and 59% for 0.8, 1.6, 2.4, and 3.2 g N/m2, respectively.
Little or no research information exists in the literature regarding recommended seeding rates of improved turf-type buffalograss (Buchloë dactyloides) cultivars, like `Bowie'. This research was conducted to determine the effect of bur seeding rate on turfgrass establishment of `Bowie' buffalograss. Two experiments were initiated on 21 July 2002 on diverse sites at the John Seaton Anderson Turfgrass Research Facility located near Mead, Nebr. Bur seeding rate effects on turfgrass quality, shoot density and cover, and seedling density were evaluated during the 2002 and 2003 growing seasons. Burs were seeded at 2.5, 5, 10, 20, and 40 g·m–2 (0.51, 1.0, 2.0, 4.1, and 8.2 lb/1000 ft2) of pure live seed (PLS). Turfgrass quality ratings increased linearly with bur seeding rate during the first growing season. However, by early in the second growing season, the response was quadratic with little or no difference in quality between 10 and 40 g·m–2. Turfgrass cover ratings responded in a similar manner to the quality ratings. Buffalograss is reported to establish slowly, taking more than one growing season to establish an acceptable level. In this study, `Bowie', a turf-type cultivar, had acceptable turfgrass quality (≥5.0) and cover (≥75%) ratings by 3 months at bur seeding rates of 5 to 40 g·m–2 of PLS, and acceptable quality and cover ratings were obtained at slightly over 1 month at rates of 20 to 40 g·m–2. These results indicate that bur seeding rates of 20 to 40 g·m–2 are advisable where rapid establishment of turf-type buffalograss is desired, and rates as low as 5 g·m–2 can be used when establishment within two growing seasons is deemed reasonable.
Abstract
Veronica repens was evaluated in a field study comparing herbicide effects on ground cover establishment. Herbicides were applied 1 day before ground covers were transplanted. Ground cover transplant root systems were either dipped or not dipped in an activated charcoal slurry prior to planting. There was a significant interaction between herbicide and charcoal treatment. Dichlobenil, chlorsulfuron, and simazine caused significant injury and reduced surface coverage. Transplants dipped in activated charcoal and treated with dichlobenil or chlorsulfuron had as much as three times less injury and produced 24% greater surface coverage than those without activated charcoal. DCPA, oxadiazon, and trifluralin caused little herbicide injury or ground cover stand reduction, and activated charcoal preconditioning did not influence their responses. These results indicate a broad herbicide range could be used with the activated charcoal root system dip procedure during Veronica repens establishment. Chemical names used: dimethyl tetrachloroterephthalate (DCPA), 2,6-dichlorobenzonitrile (dichlobenil); 2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide (chlorsulfuron); 3-[2,4-dichloro-5-(1-methyle-thoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2(3H)-one (oxadiazon); 6-chloro-N, N’-diethyl-1,3,5-triazine-2,4-diamine (simazine); α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin).
Abstract
Alkaline soils in Nebraska reduce crop yields and lower aesthetic values of ornamentals and turf (2). Chlorosis associated with alkaline soils occurs in many plants and influences plant growth and development by reducing photosynthetic efficiency (1). Data for turfgrass species and cultivar growth at high pH would be useful.