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- Author or Editor: R. C. Shearman x
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
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).
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.
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
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.
Abstract
Bensulide [0,0-diisopropyl phosphorodithioate S ester with N-2-mercaptoethyl) benzenesulfonamide] at 13.6 kg/ha reduced sod transplant rooting of ‘Park’, ‘Merion’, and ‘Baron’ Kentucky bluegrass (Poa pratensis L.) when applied either to sod or sodbed. Prosulfalin [N-[[4-(dipropylamino)-3,5-dinitrophenyl] -S,S -dimethylysulfilimine] at 2.3 kg/ha applied to the sodbed reduced sod transplant rooting of ‘Park’ and ‘Baron’. Benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine) at 2.3 kg/ha reduced rooting of ‘Baron’ when applied to the sodbed. Sod transplant rooting of ‘Baron’ was significantly reduced by siduron [l-(2-methylcyclohexyl)-3-phenylurea] at 13.6 kg/ha, oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropyoxyphenyl)-△2-1,3,4-oxadizolin-5-one] at 4.6 kg/ha, prosulfalin at 2.3 kg/ha, and benefin at 2.3 kg/ha when applied to sod prior to transplanting. ‘Merion’ and ‘Park’ were not influenced by these treatments. Regardless of herbicide treatment, ‘Baron’ had a lower sod transplant rooting strength when compared to ‘Park’ and ‘Merion’.
Abstract
Ammonia (NH3) volatilization was determined from 15N-labeled urea applied foliarly in 35 ml·m−2 water at 1.7 and 3.4 g N/m2 to a ’Park’ Kentucky bluegrass (Poa pratensis L.) turf that was grown on Sharpsburg silty clay loam (Typic Argiudoll). Field measurements of NH3 volatilization were made 1, 5, 9, 13, and 25 hr after treatment (HAT). Additional volatilization measurements were made at 2, 3, and 4 days after treatment (DAT). Maximum NH3 losses of 9.7 and 23.0 mg N/m2 per hr at 5 and 25 HAT occurred with the 3.4 g N/m2 treatment. Maximum volatilization during 25 HAT coincided with periods of high leaf surface moisture followed by rapid drying. On the second day after treatment, the maximum NH3 loss of 14.0 mg N/m2 per hr occurred from the 3.4 g N/m2 treatment. Cumulative 4-day NH3 volatilization losses for foliar-applied urea at 1.7 and 3.4 g N/m2 were 35% and 31%.
Golfers are demanding increased ball roll distances on a daily basis, but cultural practices to achieve this often are detrimental to the green. One option for increasing ball roll distance without altering cultural practices may be to select creeping bentgrass genotypes that provide less resistance to ball roll. Studies were conducted at the John Seaton Anderson Turfgrass and Ornamental Research Facility near Ithaca, Neb., and at the Rocky Ford Turfgrass Research Facility in Manhattan, Kans., to determine genotype and seasonal influences on golf ball roll distance. Eighteen creeping bentgrass (Agrostis palustris Huds.) genotypes were evaluated. Genotype was not a significant source of variability, but the location × season interaction was. Significant seasonal differences in ball roll occurred at both locations. Ball roll distances for spring, summer, and fall were 98, 15, and 31 cm greater at the Nebraska test location than at the Kansas site. Correlations between turfgrass visual quality and ball roll distance were not significant. Therefore, the use of genotypes exhibiting high turfgrass visual quality will not necessarily result in longer ball rolls. Since there were no season × genotype or genotype × location interactions, ball roll distance on genotypes at each location changed similarly with season. Genotype selection appears to have little influence on ball roll distance under the conditions tested at these two locations.