Date of Award

5-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Division of Agriculture (SAFES)

Committee Member

Haibo Liu, Committee Chair

Committee Member

Sarah A White

Committee Member

Hong Luo

Abstract

Shade, an environmental stress, can potentially have negative impacts on warm-season turfgrasses. Over shading has the potential to become problematic, leading to deterioration of turf quality and tolerance. Therefore, additional management practices may be implemented under shade to retain an acceptable turf quality and combat stress. Foliar applied iron (Fe) enhances turfgrass color and may potentially be implemented as a management practice to retain acceptable turf quality under shade. Therefore, objectives of this thesis were to investigate the responses of two warm-season turfgrasses to different levels of Fe under varying levels of shade under both greenhouse and field conditions.

Field research was conducted in 2017 and repeated in 2018, on two warm-season turfgrasses to examine impacts of iron fertilization under full-sun and shade in the southern transition zone. ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr] and ‘Tifgrand’ bermudagrass (Cynodon transvaalensis Burt-Davy x C. dactylon) were grown on native clayey (Cecil sandy loam) soil at the Clemson University Research Plots in Clemson, SC, under full-sun and 40% continuous shade, and treated with four levels of foliar applied ferrous sulfate (FeSO4 • H2O), control, 1 kg ha-1 Fe, 3 kg ha-1 Fe, and 5 kg ha-1 Fe. The research was broken down into four independent studies due to geographical differences in location, Diamond zoysiagrass under shade, Tifgrand bermudagrass under shade, Diamond zoysiagrass under full-sun, and Tifgrand bermudagrass under full-sun. Each study was assessed based on visual turfgrass quality (TQ), normalized difference vegetative index (NDVI), shoot chlorophyll index, clipping yield, shoot tissue nutrient concentrations, ash root biomass, total root and verdure biomass, and verdure bulk density. Fe treatments had the greatest impact on TQ compared to other parameters measured, observed to be significantly higher where Fe was applied but, short-lived on vigorously growing turfgrasses. Overall, Fe fertilization appears to be beneficial on turf grown under full-sun to moderate shade by enhancing turf color and quality.

Two greenhouse studies were conducted at the Clemson University Greenhouse Research Complex in Clemson, SC, to examine the impacts of shade and iron fertilization had on two warm-season turfgrasses under greenhouse conditions. ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr] and ‘Tifgrand’ bermudagrass (Cynodon transvaalensis Burt-Davy x C. dactylon) were grown in pure sand, under full-sun, 40%, and 60% continuous shade, and treated with three levels of foliar applied ferrous sulfate (FeSO4 • H2O), control, 3 kg ha-1 Fe, and 5 kg ha-1 Fe. Turfgrasses were evaluated based on the parameters of visual turfgrass quality (TQ), normalized difference vegetative index (NDVI), shoot chlorophyll index, clipping yield, tissue nutrient concentrations, total root and verdure biomass, and total biomass. Turf cultivar and shade level significantly impacted TQ and NDVI most weeks; whereas, Fe only significantly impacted TQ most weeks. Diamond had consistently higher TQ scores than Tifgrand, both displayed acceptable TQ under light to moderate shade, and unacceptable TQ was only shown under 60% shade. Treatments of 3 and 5 kg ha-1 Fe were shown to produce higher TQ scores than the control, demonstrating that Fe fertilization may have beneficial impacts, improving TQ, of shaded to non-shaded turfgrasses.

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