Date of Graduation

12-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Plant Science (PhD)

Degree Level

Graduate

Department

Plant Pathology

Advisor/Mentor

Douglas E. Karcher

Committee Member

Michael D. Richardson

Second Committee Member

Kristofor R. Brye

Third Committee Member

Donald M. Johnson

Fourth Committee Member

Terry N. Spurlock

Keywords

Drought Tolerant, Irrigation, Irrigation Sensors, Lawn, Turfgrass, Water Conservation

Abstract

Turfgrass lawns are widely used in residential and commercial landscapes, providing many environmental, aesthetic, and recreational benefits. However, concerns and scrutiny arise with perceived maintenance requirements, particularly with regards to irrigation. It is important to manage irrigation in order to maximize water conservation without significantly reducing lawn quality. A series of field and greenhouse studies were conducted to investigate how water usage might be reduced in irrigation practices with the following proposed objectives: 1) evaluate the use of rain and soil moisture sensors in a humid transition zone environment; 2) evaluate the effects of chronic drought stress between drought-resistant and drought-sensitive varieties of tall fescue (Festuca arundinacea Schreb.; TF) and Kentucky bluegrass (Poa pratensis L.; KBG) under field conditions; 3) investigate field performance differences between KBG varieties, varying in drought-resistance, under variable amounts of deficit irrigation; 4) evaluate the impact of irrigation frequency on the establishment of seeded cool-season turfgrasses varying in drought resistance; 5) and evaluate the impact of deficit irrigation for establishing seeded TF cultivars, varying in drought resistance, in the field. On average, rain sensors reduced irrigation by 22.5% and soil moisture sensors reduced irrigation by 66.5% with no decline in turfgrass quality with no decline in lawn quality. Environmental conditions greatly influenced the impact of chronic drought stress on TF and KBG, as intense and timely rains occurred. As a result, minimal differences in turfgrass quality or green turfgrass coverage were observed. Under prolonged, chronic drought stress, drought-resistant KBG exhibited greater coverage than drought-sensitive KBG at lower levels of deficit irrigation. During establishment, drought-resistant perennial ryegrass (Lolium perenne L.), TF, and KBG varieties irrigated every two days, exhibited similar turfgrass coverage to when irrigated daily. Intraspecific drought-resistance differences of mature TF and KBG in previous findings were not consistently observed during establishment. Tall fescue irrigated at 75% of reference evapotranspiration exhibited similar coverage as irrigation replacing 100% reference evapotranspiration, which could be a useful guideline regarding irrigation requirements for establishing TF from seed. Overall, these findings demonstrate the great potential to reduce water use in irrigation practices used in establishing and maintaining turfgrass lawns.

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