International Turfgrass Society Research Journal最新文献

A plant biostimulant is a natural substance or microorganism applied to plants or soil to enhance growth and stress tolerance. The objective of this study was to measure the effect of six commercial plant biostimulants on root and shoot production in seedlings of three cool-season turf species grown in a controlled environment. Lolium perenne L., Agrostis palustris Huds., and Schedonorus arundinaceus Schreb. were seeded into tobacco float trays and, after germination, were installed in a hydroponic system receiving a half-dose Hoagland solution. Fifteen days after seeding, seedlings were treated with six different plant biostimulants applied within each float tray and then grown in a greenhouse for 25 d, following a split-plot design. Photosynthetically active radiation, air temperature, and humidity were monitored for the duration of the study. The experiment was conducted twice. Fresh weight, dry weight, and total nonstructural carbohydrates were measured. The study showed that humic substances and complex organic materials had a positive effect on turfgrass performance, and there are species differences in the responses of turfgrass.

Six 1-yr observational studies were conducted from 2001 to 2006 at the Hancock Turfgrass Research Center in East Lansing, MI to characterize the timing, duration, and amplitude of annual bluegrass (AB) (Poa annua L.) seedhead emergence in a 10- to 15-yr-old AB fairway. The objective of this research was to collect data that could be used in the development of a growing degree-day (GDD) model to predict AB seedhead emergence at other locations by using readily available weather station data. New GDD models were compared with previously published models. Plots were established on two adjacent perennial stands of AB maintained at 1.5 cm, receiving 0.5 to 0.6 cm of automatic daily irrigation throughout the growing season and 120 kg N ha^–1 yr^–1 from 2001 to 2006. The soil type is a Marlette sandy loam (fine-loamy, mixed, semiactive, mesic Oxyaquic Glossudalf). Line intersects and visual estimations of seedhead cover were evaluated multiple times throughout the spring seedhead emergence period. A base temperature of –5 °C most accurately predicted the onset, peak duration, and completion of the AB seedhead emergence period for all 5 yr. The final model flowering rate = (–3.331599 × 10^–6 × gdd²⁾ + (6.968782 × 10–3 × gdd) + –2.841894, accurately predicted (R² = .64) flowering stages of an AB fairway turf over 6 yr in Michigan.

Turfgrass managers have anecdotally reported decreased efficacy of DMI fungicides for the control of Microdochium patch and pink snow mold at golf courses in British Columbia, Canada. Isolates of Microdochium nivale from these locations, along with isolates collected in Ontario, Canada, were tested for their sensitivity to the fungicide propiconazole [1-([2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]methyl)-1,2,4-triazole]. Ontario isolates (47) had values for effective concentration causing 50% growth inhibition (EC₅₀) ranging from <0.001 to 0.89 µg ml^–1. In comparison, British Columbia isolates (50) had an EC₅₀ range of 0.02 to 8.7 µg ml^–1. Sensitivity testing with a discriminatory concentration (0.1 µg ml^–1) of a larger set of isolates revealed that 24% of Ontario isolates (43 of 181) and 77% of British Columbia isolates (55 of 71) exhibited resistance to propiconazole (>50% growth on 0.1 µg ml^–1 compared to non-amended media). Because of the cool, wet climate of coastal British Columbia, turfgrass managers use more applications of fungicides annually, including propiconazole, to control diseases caused by M. nivale, and this has resulted in a greater proportion of isolates being resistant to propiconazole. In contrast, Ontario has a less favorable climate for these diseases, with accordingly fewer fungicide applications directed toward this pathogen and hence less risk of fungicide resistance developing.

A trial was conducted to assess the suitability of a novel plastic geocellular drainage layer (Permavoid) as a replacement for a conventional gravel layer in a high-quality sports pitch. The trial was conducted during the 2014–2015 and 2015–2016 United Kingdom football (soccer) seasons. Perennial ryegrass (Lolium perenne L.) was grown under five different rootzone depth treatments (50, 100, 200, and 300 mm over Permavoid and 300 mm over gravel as a control representing current practices). These were repeated for two contrasting rootzone types. The trial area was subjected to artificial football-style wear throughout each playing season, with irrigation and nutritional inputs as would be normal for a high-quality football pitch. Infiltration rates, rootzone moisture content, turf cover and tractional strength for the 200- to 300-mm rootzone over Permavoid and 300 mm over gravel were the same throughout the trial. The replacement of the gravel drainage layer with Permavoid had no negative effect on the rootzone's hydraulic characteristics or turfgrass growth over the 2-yr study period. In addition, it may be possible to use shallower rootzone depths in some circumstances, reducing the volume of material needed for construction. Shallower rootzones (50–100 mm) experienced greater fluctuations in rootzone moisture content, which was likely to be directly related to rootzone depth. Rootzone type had a minor effect, with finer rootzones holding onto more moisture and allowing slightly stronger turf. Therefore, when managing shallower and/or coarser rootzones, maintenance programs need to reflect the moisture and nutrient retention characteristics of these growing media.

Enhanced nitrogen use efficiency (NUE) in turfgrass systems comprises several factors, including more efficient uptake and assimilation of applied nitrogen (N), as well as reduced N losses to the environment. The objectives of the current research were to evaluate the inter- and intraspecific variation in N use parameters in two Agrostis species, creeping bentgrass (Agrostis stolonifera L.) and velvet bentgrass (Agrostis canina L.), under field and controlled environmental conditions. Measurements included leaf NUE (g dry matter mg^–1 N), leaf N content (mg g^–1 dry matter), leaf and root nitrate reductase activity (NRA)(μmol NO₂^– g^–1 fresh weight h^–1), and root nitrate uptake rate (NUR). Velvet bentgrass cultivars exhibited higher leaf N content and therefore lower leaf NUE than creeping bentgrass cultivars in the field and in a nutrient solution. Differences in leaf NRA were only observed in Agrostis species and cultivars in the field, with higher NRA observed in creeping bentgrass. Velvet bentgrass cultivars grown in a nutrient solution exhibited a 50% higher root NUR than creeping bentgrass, with leaf NRA and N content increasing and leaf NUE decreasing in Agrostis under higher NO₃^– supply.