Browsing by Author "Kosiarski, Kelly"

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    Photosynthetic Rate and Root Growth Responses to Ascophyllum nodosum Extract–based Biostimulant in Creeping Bentgrass under Heat and Drought Stress
    Zhang, Xunzhong; Taylor, Zachary; Goatley, Mike; Wang, Kehua; Brown, Isabel; Kosiarski, Kelly (American Society for Horticultural Science, 2023-08-01)
    Creeping bentgrass (Agrostis stolonifera) experiences quality decline during summer in the United States transition zone and warmer regions. Various bioproducts have been used to improve creeping bentgrass performance and to mitigate effects of summer stress in the United States transition zone. This 2-year study was carried out to examine if foliar application of seaweed extract (SWE; Ascophyllum nodosum)-based biostimulant UtilizeVR could enhance creeping bentgrass nitrate reductase (NaR) activity, and root viability under heat and drought stress conditions. The UtilizeVR was sprayed biweekly on creeping bentgrass foliage at 0, 29, 58, 87, and 116 mL.m22, with application volume of 815 L.ha22. Two weeks after first application, plants were exposed to heat (35/25◦C, day/night) and drought stress (40% to 50% evapotranspiration replacement) conditions for 42 days in an environment-controlled growth chamber. In general, the abiotic stress caused turf quality reduction. Foliar application of UtilizeVR at 58, 87, and 116 mL.m22 increased turf quality, leaf color ratings, leaf chlorophyll, carotenoid content, and net photosynthetic rate (Pn). UtilizeVR at 58, 87, and 116 mL.m22 increased NaR activity by 26.5%, 16.3%, and 16.3%, respectively, when compared with the control. UtilizeVR at 58, 87, and 116 mL.m22 increased root biomass, root length, surface area (SA), and root volume when compared with the control. UtilizeVR at 58 and 87 mL.m22 improved root viability by 16.3% and 30.9%, respectively, when compared with the control. Our data indicate that the SWE-based biostimulant UtilizeVR improves nitrogen (N) metabolism and root viability. UtilizeVR treatment at 58 mL.m22 biweekly can be considered an effective approach for improving creeping bentgrass performance during summer stress.
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    Seaweed Extract-based Biostimulant Impacts on Nitrate Reductase Activity and Root Viability of Ultradwarf Bermudagrass Subjected to Heat and Drought Stress
    Zhang, Xunzhong; Taylor, Zachary; Goatley, Mike; Booth, Jordan; Brown, Isabel; Kosiarski, Kelly (American Society for Horticultural Science, 2022-10-01)
    Bermudagrass is a warm-season turfgrass species widely used for sports fields, home lawns, and golf courses. Ultradwarf bermudagrass has been used for golf course greens, but its quality declines with abiotic stresses. This 2-year study was designed to investigate if foliar applications of seaweed extract-based biostimulant UtilizeVR could improve ultradwarf bermudagrass photosynthetic function, nitrate reductase activity, root growth, and root function while under heat stress and drought stress conditions. UtilizeVR was applied to ultradwarf bermudagrass canopy at 0, 88, 117, 175, and 234 lL•m22. Two weeks after the initial application of UtilizeVR , bermudagrass was subjected to heat (40/36 ◦C, day/night) and drought stress (40–50% evapotranspiration replacement) for up to 42 days. Heat stress and drought stress caused decline of the turf quality. Foliar application of UtilizeVR at 117, 175, and 234 lL•m22 biweekly consistently improved turf quality and leaf color ratings and increased leaf chlorophyll and carotenoid concentrations, net photosynthetic rate, nitrate reductase activity, and root growth and viability. On average, UtilizeVR at 117, 175, and 234 lL•m22 increased turf quality ratings by 9.1%, 12.1%, and 10.6%, respectively, net photosynthetic rates by 32.4%, 45.0%, and 35.0%, respectively, and nitrate reductase activity by 16.7%, 18.8%, and 14.6%, respectively, compared with the control. UtilizeVR at 117, 175, and 234 lL•m22 increased the root biomass, root length, surface area, and root volume compared with the control. UtilizeVR at 88, 117, 175, and 234 lL•m22 increased root viability by 46.2%, 73.1%, 88.5%, and 74.4%, respectively, relative to the control. The results of this study suggest that seaweed extract-based biostimulant UtilizeVR improves nitrogen metabolism, photosynthetic function, root growth, and root viability. Foliar application of UtilizeVR at rates between 117 and 175 lL•m22 biweekly can be considered an effective approach to improving ultradwarf bermudagrass performance under heat stress and drought stress environments.
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    Silicon Improves Heat and Drought Stress Tolerance Associated with Antioxidant Enzyme Activity and Root Viability in Creeping Bentgrass (Agrostis stolonifera L.)
    Zhang, Xunzhong; Goatley, Mike; Wang, Kehua; Goddard, Ben; Harvey, Rose; Brown, Isabel; Kosiarski, Kelly (MDPI, 2024-05-30)
    Creeping bentgrass (Agrostis stolonifera L.) is an important cool-season turfgrass species widely used for golf course putting greens; however, it experiences summer stress and quality decline in the U.S. transition zone and other regions with similar climates. Silicon (Si) may improve the abiotic stress of creeping bentgrass, but the mechanism of its impact on plant drought and heat tolerance is not well understood, and a few studies have reported on the effects of Si on creeping bentgrass drought and heat tolerance. The objectives of this study were to determine the effects of Ortho-silicic acid (Ortho-Si) on antioxidant metabolism and root growth characteristics and viability in creeping bentgrass under drought and heat-stress conditions. The three treatments, including control, Ortho-Si at 0.16 mL m−2 and 0.32 mL m−2, were applied biweekly to creeping bentgrass. Foliar application of the Ortho-Si exhibited beneficial effects on turf quality, physiological fitness, and root growth in creeping bentgrass. The Ortho-Si application at 0.16 mL m−2 and 0.32 mL m−2 improved turf quality ratings by 9.5% and 11.1%, respectively, photochemical efficiency (PE) by 6.9% and 8.5%, respectively, chlorophyll content by 27.1% and 29.9%, and carotenoids content by 25.5% and 27.2%, respectively, when compared to the control at the end of the trial. The Ortho-Si treatments enhanced antioxidant enzyme activity; the highest amount, in particular, increased superoxide dismutase (SOD) activity by 32.8%, catalase (CAT) by 12.8%, and ascorbate peroxidase (APX) activity by 37.4%, as compared to the control. The Ortho-Si application reduced leaf hydrogen peroxide (H2O2) concentration relative to the control. In addition, exogenous Ortho-Si improved leaf Si concentration. The Ortho-Si application at 0.32 mL m−2 increased root biomass by 52.7% and viability by 89.3% relative to the control. Overall, Ortho-Si at 0.32 mL m−2 had greater beneficial effects than the low rate (0.16 mL m−2). Exogenous Si may improve drought and heat tolerance by protecting photosynthetic function, enhancing the activities of leaf antioxidant enzymes, and stimulating root growth, viability, and Si uptake. The results of this study suggest that foliar application of Ortho-Si at 0.32 mL m−2 may be considered to be an effective approach to improve turf quality and physiological fitness of creeping bentgrass during the summer months in the U.S. transition zone and other regions with similar climates.