Papers by IAN ARIEL JARQUIN RODRIGUEZ
HortScience, 2005
Use of creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)] on golf greens has e... more Use of creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)] on golf greens has expanded into the hotter, more humid regions of the United States where its quality is often low during summer months. The summer decline in bentgrass quality may be partially attributed to respiration rates exceeding photosynthesis during periods of supraoptimal temperatures and adverse soil conditions, such as excessive CO2 and inadequate O2 levels. The objectives of this study were to examine the effects of high temperature, high soil CO2, and irrigation scheduling on creeping bentgrass growth. A growth chamber study was conducted using `A-1' creeping bentgrass. Treatments included all combinations of three day/night temperature regimes (26.5/21 °C, 29.5/24 °C, and 32/26.5 °C), three irrigation schedules (field capacity daily, field capacity every two d, and half field capacity daily), and four soil CO2 injection levels (10%, 5%, 0.03%, and a noinjection control). Creeping bentgras...
HortScience, 2000
Establishment of an acceptable turfgrass quality on sand-based golf putting greens presents major... more Establishment of an acceptable turfgrass quality on sand-based golf putting greens presents major agronomic and environmental challenges to turfgrass managers. The objective of this study was to evaluate of five N:P:K fertilizer ratios to aid in the establishment of bermudagrass on sand-peat (85:15 v/v). `Floradwarf' and `Tifdwarf' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt-Davy] were sprigged in Aug. 1996 at the Envirogreen in Gainesville, Fla. `Tifeagle' and `Tifway' bermudagrass were sprigged in May 1999 at Clemson Univ. research green in Clemson, S.C. Treatments consisted of N:P2O5:K2O ratios of 1:0:1, 1:0:2, 1:1:1, 1:2:1, and 1:3:1 applied based on an N rate of 49 kg/ha per week. Treatments were applied weekly for 7 weeks. In Gainesville, the best growth rate was achieved from the 1:1:1 ratio of N:P2O5:K2O. While the 1:2:1 and 1:3:1 plots filled in well, they did not experience the same coverage rates as plots fertilized with the 1:1:1 ra...
HortScience, 2000
Because high rates of nitrogen fertility are necessary for producing high-quality turfgrasses, qu... more Because high rates of nitrogen fertility are necessary for producing high-quality turfgrasses, quick, reliable methods of determining the N status of turfgrasses would be valuable management tools. The objective of this study was to evaluate the capacity of a hand-held chlorophyll meter (SPAD-502) to provide a relative index of chlorophyll concentrations, N concentrations, and visual quality in St. Augustinegrass [Stenotaphrum secondatum (Walt.) Kuntze]. Two experiments were conducted in a greenhouse in 1998 to evaluate the utility of SPAD readings. Established pots of `Floratam' were subjected to weekly foliar Fe treatments at Fe rates of 0 and 0.17 kg·ha–1 for 4 weeks. Six weekly nitrogen fertilizer treatments were applied in the form of ammonium sulfate at N rates of 0, 5.75, 11.5, 17.25, and 23 kg·ha–1 for 4 weeks. Greenhouse SPAD readings were not affected by Fe treatment, but N treatments resulted in differences in SPAD readings, visual quality, and chlorophyll concentrati...
HortScience, 2002
For drainage, turfgrass is often established on sand-based soils, which are typically nutrient-de... more For drainage, turfgrass is often established on sand-based soils, which are typically nutrient-deficient and require supplemental fertilization. The objective of this study was to determine the optimum N-P-K fertilizer ratio for establishing bermudagrass from sprigs in sand. `FloraDwarf' and `Tifdwarf' bermudagrasses [Cynodon dactylon (L.) Pers. × C. transvaalensis Burt-Davy] were sprigged on a United States Golf Association (USGA) green [85 sand: 15 peat (v/v)] in Aug. 1996 at the Univ. of Florida's Envirogreen in Gainesville, Fla. `TifEagle' bermudagrass was sprigged on a USGA green [85 sand: 15 peat (v/v)] and `Tifway' bermudagrass [C. dactylon (L.) Pers.] was sprigged on native soil at Clemson Univ. in Clemson, S.C. in May 1999. Treatments consisted of fertilizer ratios of 1N-0P-0.8K, 1N-0P-1.7K, 1N-0.4P-0.8K, 1N-0.9P-0.8K, and 1N-1.3P-0.8K applied based on a N rate of 49 kg·ha-1/week for 7 weeks. Growth differences were apparent among cultivars. A 1N-0P-0.8K...
Http Www Theses Fr, 2009
In this work emphasis is put on the clarification of the complex microstructural evolution in mul... more In this work emphasis is put on the clarification of the complex microstructural evolution in multiphase lightweight steels. In the first part of this investigation detailed sequences of phase transformations are proposed and the domains where austenite is stable are given. Then isothermal growth kinetics of austenite was measured. Kinetics was modeled with known binary and ternary models. The DICTRA software provided only a qualitative description due to the shortcomings of the thermodynamic database. A deep-etching procedure together with the EBSD technique provided a correlation between morphology of the K-phase and orientation relationships with ferrite. Isothermal growth kinetics was measured in two morphologies of the K-phase. Modeling of the K-phase required a better knowledge of phase equilibria to yield proper results.
Agronomy Journal, 2000
Due to the high rates of N fertility necessary for producing high-quality turfgrasses, quick, rel... more Due to the high rates of N fertility necessary for producing high-quality turfgrasses, quick, reliable methods of determining the N status of turfgrasses would be valuable management tools. The first objective of this study was to evaluate the use of near infrared reflectance spectroscopy (NIRS) to schedule N fertilization on two dwarf-type bermudagrasses [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy]. The second objective was to test the accuracy of NIRS-predicted mineral tissue concentrations. The third objective was to study the effect of N fertility on thatch development. Tifdwarf' and FloraDwarf' bermudagrasses grown on sand-peat (9:1 by volume) were subjected to five treatments using time, NIRS-predicted N thresholds, and a visual quality rating threshold to schedule applications of (NH 4 ) 2 SO 4 for 20 wk per growing season in 1997 and 1998. There were positive linear relationships between total Kjeldahi nitrogen (TKN) and NIRS-predicted N in 1997 (r 2 = 0.76; slope = 0.96) and 1998 (r 2 = 0.92; slope = 1.06). NIRS-scheduled fertility resulted in similar quality with less fertilizer than time or visual quality-based fertility. The NIRS mineral concentration predictions for K, Ca, Mg, Fe, Zn, Mn, and Cu were positively correlated with traditional laboratory methods, but there was not sufficient precision in measurements to use NIRS for determination of these nutrients. Thatch development and yields were greater in treatments receiving higher rates of fertilizers, suggesting that excessive growth rates due to high rates of applied fertilizer may have contributed to thatch development.
Agronomy Journal, 2005
Preferential use of creeping bentgrass [Agrostis stoloniferous L. Applying light, frequent amount... more Preferential use of creeping bentgrass [Agrostis stoloniferous L. Applying light, frequent amounts of water (syringing) var. palustris (Huds.)] on golf putting greens has expanded into the is a management practice often utilized on bentgrass hotter, more environmentally stressful regions of the southeastern putting greens under heat stress conditions. This prac-United States where turfgrass decline is problematic during summer months. Methods of reducing temperatures in the putting green micro-tice is based on the concept of evaporative cooling. Syringclimate would enhance bentgrass survival under heat stress conditions. ing creeping bentgrass has been shown to produce modest The objectives of this study were to evaluate the bentgrass putting (1 to 2ЊC) turf mat temperature reductions (Duff and green microclimate under combined misting and/or subsurface fan Beard, 1966) or no reduction unless the turf had already systems with surface fans. Field studies were conducted in the summers wilted (DiPaola, 1984). No information is available on of 2001 and 2002 on a 'Crenshaw' creeping bentgrass putting green the use of water mist in a fan's air stream to reduce located in Clemson, SC. Treatments consisted of surface fan only, canopy and soil temperatures. surface fan plus misting, surface fan plus subsurface fan, and surface Forcing air into a USGA (United States Golf Associafan plus misting and subsurface fan. Fan treatments were applied tion) green rootzone through subsurface drain lines has from 1100 to 1500 h on days when temperatures were Ն29.5؇C, there been shown to reduce soil temperatures. A preliminary was no visible cloud cover, and wind speed Ͻ 1.0 m s Ϫ1. Surface fan study noted forcing air into the rootzone reduced soil plus misting treatments reduced putting green canopy, soil surface, and soil temperatures by as much as 9, 7, and 6؇C, respectively, while temperatures 2 to 3ЊC at a depth of 5 cm in the afternoon increasing canopy relative humidity and soil moisture content. Bene-(Dodd et al., 1999). Similar experiments also reported fits were generally observed over a range of 5 m from the fan. These soil temperature reductions as great as 2.5ЊC at 10-cm treatments demonstrate great potential for improving canopy and soil depth in USGA bentgrass greens (Bigelow et al., 2001). microclimate conditions influencing bentgrass survival in a heat stress Using misting and/or subsurface fans with surface fans environment. Surprisingly, the use of subsurface fans did not enhance may provide effective means of reducing plant and soil the cooling effect provided by surface fans. Fan/mist systems should be temperatures of bentgrass putting greens in the southern investigated further to determine possible disease occurrence during United States. The objective of this study was to evaluextended use periods. ate, under heat stress conditions, the effects of misting and/or subsurface air movement on the bentgrass putting green microclimate when used in combination with
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Papers by IAN ARIEL JARQUIN RODRIGUEZ