Lew Wentz FoundationHorticulture and Landscape Architectur

Amgain, Naba

Fontanier, Charles H.

Frizzell, Robert Nash

English

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www.postersession.comwww.postersession.comDiurnal Patterns in Light Quality and Photosynthesis of Creeping Bentgrass under Tree ShadeRobert Frizzell, Naba Amgain, Dr. Charles Fontanier|Department of Horticulture and Landscape Architecture, Oklahoma State University| robert.frizzell@okstate.eduReferences1. Bell, G.E., and T.K. Danneberger. 1999. Temporal shade on creeping bentgrass turf. Crop Sci. 39: 1142-11462. Dudeck, A.E., and C.H. Peacock. 1992. Shade and turfgrass culture. In D.V. Waddington et al. (ed.) Turfgrass. Agron. Monogr. 32. ASA, CSSA, and SSSA, Madison, WI.Introduction• Creeping bentgrass (Agrostis stolonifera L.) is a cool season, perennial, stoloniferous turfgrass primarily used for putting greens in the transition zone.• Most putting greens are surrounded by trees, which cause shading issues.• Shade diminishes the health of turfgrass by reducing photosynthetically active radiation (PAR) required for the survival of the plant (Bell and Danneberger 1999).• Shade is known to reduce plant carbohydrate reserves, the growth of roots, shoots, rhizomes, and stolons, increases stem elongation, and results in longer leaf sheaths (Dudeck and Peacock 1992).• Morning versus afternoon shade is speculated to affect turf performance differently.• Research is needed to determine if morning or afternoon shade is more detrimental to creeping bentgrass health.Objective• Evaluate net canopy photosynthesis of creeping bentgrass during morning or afternoon shade in comparison to non-shaded conditions.• Characterize light quality under deciduous tree shade.Material and Methods• Location: Oklahoma State University Turfgrass Research Center; Stillwater, OK• Turfgrass: ‘007’ creeping bentgrass• Creeping bentgrass plugs were propagated on July 1, 2018.• Plugs were grown in a greenhouse until August 15, 2018 and placed into the field under different treatments.• Data were collected on September 20 and 27, 2018.• Canopy photosynthesis and respiration were measured using the Li-COR 6400XT (LI-COR Biosciences/Lincoln,NE) fitted with an Arabidopsis chamber.• PAR was measured using a handheld full-spectrum quantum sensor (Spectrum MQ-501) at time of measurement.• A spectrometer (WaveGo-VIS-50)  measured the sunlight's wavelength, frequency, and energy.ResultsAcknowledgementsI would like to thank the Lew Wentz Foundation for the funding and support of this research project.Fig. 3. Spectrometer measuring light wavelengths and frequency. Fig. 2. Turfgrass pot measurements taken with the LI-COR 6400XT inside the Arabidopsis chamber.Fig. 1. Visual appearance of each treatment on 20 Sept. 2018 for a) full sun, b) morning shade, and c) afternoon shade.Fig. 4. A) Spectral distribution of full sun @10AM (red to far-red = 1.05 B) Spectral distribution of full shade @3:30PM (red to far-red = 0.44)Fig. 5. A) Spectral distribution of morning shade @10AM (red to far-red = 0.63) B) Spectral distribution of afternoon shade @3:30PM (red to far-red = 0.79)Material and Methods (cont.)• Pot Specifications: 2.5 cm in diameter, pots filled with sand meeting USGA specifications• Mowing: 3 times weekly at 4.5 to 5mm• 20-20-20 fertilizer was applied every two weeks• Treatments were ‘full sun’, ‘full shade’, ‘morning sun/afternoon shade’, and ‘morning shade/afternoon sun’ environments.• Four replicate pots of each treatment were used for measurements.BFig. 6. Rate of photosynthesis for morning and afternoon shade treatments. PAR varied due to the timing of sun and shade for each treatment.• Red to far-red ratios were greatly influenced by shade.• Shade caused a lower ratio of red to far-red light (Fig. 4 and 5) suggesting blue, green, and red light was absorbed by the trees but far-red light was transmitted or reflected to the turfgrass canopy.• Turfgrass pots that experienced high amounts of PAR had higher rates of net photosynthesis.• Net photosynthesis plateaued at approximately 1000 nm regardless of time of day.• There was no clear evidence that morning or afternoon shade differed in relative importance to canopy net photosynthesis.Conclusion• Creeping bentgrass reached light saturation at about 50% of full sun.• The effect of shade timing on photosynthesis was inconclusive.• Future research should investigate net photosynthesis during multiple seasons of shade.a) c)b)Key FindingsTime Treatments PAR(400-700nm) 350-400nm 400-500nm 500-600nm 600-700nm 700-780nmµmol m-2 sec-110AM Full Sun 919 42 239 323 357 271Full Shade 22 3 9 8 6 18Afternoon Shade 976 42 247 344 385 302Morning Shade 54 9 25 18 12 193:30PM Full Sun 1295 63 342 455 497 103Full Shade 87 5 24 31 32 60Afternoon Shade 189 16 61 65 63 60Morning Shade 1340 62 348 473 519 407y = 4.7351ln(x) - 15.612R² = 0.6445y = 4.6672ln(x) - 14.577R² = 0.7174-10-5051015202530350 200 400 600 800 1000 1200 1400 1600 1800 2000Rate of Photosynthesis (ergs cm^-2 sec^-1)Photosynthetically Active Radiation (nm)Morning AfternoonTable 1. Summary table of PAR readings taken with the spectrometer on 5 October 2018.B

Diurnal patterns in light quality and photosynthesis on creeping bentgrass under tree shade

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Diurnal patterns in light quality and photosynthesis on creeping bentgrass under tree shade

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