INVESTIGATIONS OF TURFGRASS ABIOTIC STRESS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1019520
• Project Start Date: Oct 1, 2019
• Project End Date: Sep 30, 2024
• Program Code: [(N/A)]- (N/A)

Recipient Organization
OKLAHOMA STATE UNIVERSITY
(N/A)
STILLWATER,OK 74078

Performing Department
Horticulture & Landscape Architecture

Non Technical Summary
Turfgrasses provide numerous functional, aesthetic, and recreational benefits to society but require sufficient water for growth and survival. Drought stress is an important factor concerning the growth and survival of turfgrasses in Oklahoma. The most widely utilized warm-season turfgrass in Oklahoma is bermudagrass which can be found growing between 45° N and S latitudes in the world. In the southern United States alone, bermudagrass is grown on 30 million acres for livestock grazing, hay production, and seed/sod production. An additional 20 million acres of bermudagrass is used as turf, roadsides, and right-of-ways. Compared to other turfgrasses, bermudagrass is relatively drought resistant, however little is known about the differences in drought resistance among bermudagrass cultivars. In Oklahoma, precipitation and soil moisture do not often coincide with turfgrass plant water needs. In addition, there is much genetic diversity in bermudagrass germplasm and Oklahoma State Universityholds numerous accessions from across the world, including germplasm from China which could contribute to genetic improvement in bermudagrass drought resistance. The OSU bermudagrass breeding and development program is well established and the team utilizes both traditional and molecular breeding techniques including Amplified Fragment Length Polymorphism (AFLP) and Simple Sequence Repeat (SSR) markers using Express Sequence Tags (EST) and genomic DNA libraries from model crops to improve the abiotic stress tolerance, as well as the visual and functional performance quality, of bermudagrasses. To date, the major objective of the OSU Bermudagrass Development Team has focused on development, selection, and use of improved cultivars. More specifically, the team has focused on the development, selection, and use of bermudagrasses showing improved cold hardiness while maintaining acceptable yield and/or quality. For instance, improved turf sod cultivars such as 'Patriot' (2002), 'NorthBridge' and 'Latitude 36' (both in 2010) were selected specifically for sod strength, turf quality, and winter hardiness. Recently, 'Tahoma 31' was developed by the OSU team and was released in 2018. According to work by the Moss research team, 'Latitude 36' and 'NorthBridge' have improved drought tolerance versus other bermudagrass varieties but did not perform as well as 'Celebration' which shows improved drought resistance in Oklahoma mostly due to its ability to avoid drought via superior root growth. However, for Oklahoma, both 'Latitude 36' and 'NorthBridge' have significantly improved cold hardiness, making them a better choice to grow in Oklahoma and survive Oklahoma winters when compared to 'Celebration'. In addition, the Moss team found that 'Tahoma 31' had a lower evapotranspiration rate when compared to other turfgrass cultivars under non-limiting water condition. Past OSU cultivars have offered sod producers rapid establishment and shorter interval harvest timing compared to other bermudagrasses, thus increasing the economic potential and sustainable production. However, we must continue to address the critical issues of drought, water availability, use of alternative water sources (water quality/salt concerns), adaptation to temperature extremes, and overall environmental impact. In addition, much focus has been on the development of very high-quality turfgrasses for use on high-end sports fields and golf courses (NorthBridge, Latitude 36, Tahoma 31). There is still a need to test and select grasses that have acceptable turf quality (medium to high turf quality), with improved abiotic stress tolerance that could be used by an average consumer or green industry end user.While there has been significant progress in developing abiotic stress resistant germplasm, relatively little is known about the mechanisms of injury and resistance in response to single or combined occurrences of abiotic stress. Research is needed to study the irrigation required to maintain warm-season grasses with acceptable quality in Oklahoma. Research is needed to evaluate the turf quality and sod production traits of germplasm showing acceptable freezing tolerance. Finally, research is needed to identify bermudagrasses with acceptable quality, drought resistance, and freeze tolerance that can ultimately be used and adapted for home lawn use in Oklahoma.

Animal Health Component

95%

Research Effort Categories

Basic

5%

Applied

95%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
111	2130	1060	50%
203	2130	1020	50%

Knowledge Area
111 - Conservation and Efficient Use of Water; 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants;

Subject Of Investigation
2130 - Turf;

Field Of Science
1060 - Biology (whole systems); 1020 - Physiology;

Keywords

turfgrass

water

drought

abiotic stress

drought resistance

bermudagrass

Goals / Objectives
The goal of this project is to promote urban environmental sustainability, efficient use of water, and to reduce lawn inputs through the development, testing, and selection of bermudagrasses with improved abiotic stress tolerance for sod production and fine turf, lawn, and landscape use in Oklahoma and the U.S. transition zone. The objectives of this project are to 1) Evaluate the seasonal water requirements of bermudagrass cultivars and genotypes in Oklahoma required to maintain acceptable turfgrass quality. 2) Test and select several experimental bermudagrass genotypes for improved drought resistance and freeze tolerance. 3) Work to identify the specific plant growth characteristics related to methods of drought resistance (drought avoidance and drought tolerance) in select, superior performing bermudagrass cultivars and genotypes.

Project Methods
Objective 1: Field research plots (1 x 1 m) will be established at the OSU Turfgrass Research Facility with approximately 20 total bermudagrass entries with three replications of each genotype and will be mowed at 1.0 inch height of cut after reaching full establishment. Approximately 15 entries will be OSU experimental genotypes and approximately 5 entries will be standard, commercially available bermudagrass cultivars. Plots will be established under field rainout drought shelters (high tunnels) which allow the grasses to be grown in field soil, but will keep natural precipitation from entering the plots during the evaluation period. During establishment and grow-in, each plot will be irrigated every 2-3 days to replace 75% of reference evapotranspiration as calculated by the Oklahoma Mesonet weather station, which is located less than 0.25 miles from the research block area. In year two and after full establishment, a seasonal testing period will commence and will last approximately 12 weeks during each summer. From May to September, each individual plot will only be irrigated only when the turf quality rating declines to less than 6. At this time, only an individual plot (1 x 1 m plot area) with a turf quality rating less than 6 will be irrigated with 1.0 inch of irrigation water by hand using a water meter to deliver the appropriate number of gallons per plot. If required, the plot will be irrigated again until the turf quality returns to a rating greater than 6. Once this achieved, no further irrigation will be given to the individual plot until the turf quality once again declines below 6. With this method, the number of inches applied to each plot will be individually tracked, allowing for calculation of the number of inches of irrigation required for each entry to maintain an acceptable quality rating throughout the growing season. Plots will be irrigated as normal after the testing period to evaluate and allow plots to recover prior to the end of the growing season. The following data will be collected weekly from each field plot: Turf quality (based on the National Turfgrass Evaluation Program criteria, rated on a 1-9 scale where 1 = dead turf and 9 = excellent turf), Leaf firing (browning of grass leaves, based on percentage), Digital photographs (for analysis via SigmaScan software to calculate percent living coverage), Normalized difference vegetative index (NDVI, measurement of leaf color), Soil volumetric water content (TDR-310S, Acclima, Inc., Meridian, ID), Climate/daily weather data from the Oklahoma Mesonet system.Objective 2: Similar to objective 1, plots will be established under field rainout drought shelters (high tunnels) which allow the grasses to be grown in field soil, but will keep natural precipitation from entering the plots during the evaluation period. In year two and after full establishment, a seasonal testing period will commence and will last approximately 12 weeks during each summer. The irrigation requirement study period will begin approximately May 1 of each year and will go through approximately September 1 of each year, during which no irrigation water will be applied to the plots. The drought testing stage will last 8-12 weeks during each summer. Plots will be irrigated as normal after the drought period to evaluate drought recovery. Data will be collected as described for objective 1.Freeze testing will occur in a controlled environment. Select OSU experimental bermudagrass selections and up to four commercial standards will be included in this experiment. The methodology has been refined by scientists at OSU and has worked well in quantifying elite bermudagrasses with high turf quality and improved freeze tolerance in the OSU bermudagrass breeding program. Grasses will be grown in Cone-tainers (3.8 cm diameter by 21 cm depth) filled with a mixture of sand and topsoil (1:1, v:v) for about 12 weeks until Cone-tainers are completely covered by uniform grasses under optimum conditions. Cultural conditions will include 28°C/24°C day/night temperatures, a light intensity of 400 μmol/m2 s for 14 hrs per day, as well as sufficient N and water. After a 4-week acclimation (8/2ºC, 14-h light), a thermocouple will be inserted into the soil in the center of each Cone-tainer at 2 cm to monitor temperature with a datalogger and Cone-tainers will then be placed into a freeze chamber. The freeze chamber will be cooled rapidly to -2ºC overnight and then programmed to cool linearly at 1ºC/h for freeze treatments and the lowest temperature will reach -18 ºC. For each cultivar, three Cone-tainers will be removed from the freeze chamber at each test temperature and will be held overnight at 5ºC in the growth chamber to thaw slowly. The grasses will then be allowed to recover in the growth chamber having optimal growth temperature (28/24ºC, 14-h light) for 6 weeks to evaluate the regrowth of plants. Quantitative data for regrowth of each experimental entry and standards will be collected and used to estimate freeze tolerance. Non-linear regression will be used to estimate the midpoint (Tmid) of the sigmoidal response curve of survival vs temperature. The means of Tmid will be separated at P<0.05 and will reflect relatively freeze resistance potential. These results will quantitatively evaluate turfgrass freeze resistance and will be beneficial for screening germplasm for freezing temperature resistance.Objective 3: In years 3-5 of this research project, sod plugs of diverse genotypes and commercialized cultivars of bermudagrass (approximately 5 total entries), which will include drought resistant and drought sensitive bermudagrass germplasm identified by the field trials in Objectives 1 and 2, will be collected and planted in short soil depth lysimeters (15 cm diameter by 15 cm long) and deep soil depth lysimeters (15 cm diameter by 120 cm long). The lysimeters will be filled with a mixture of sand and topsoil (1:1, v:v) and be maintained in a greenhouse for eight weeks or until fully established. Grasses will be clipped weekly at 5 cm and will be fertilized weekly with soluble fertilizer. Plants will be watered daily during establishment and three times per week or as needed to prevent stress after initial establishment. After full establishment in the greenhouse for approximately 4-6 months, the grasses will be exposed to drought stress without clipping and fertilizing. The drought treatment will be performed by completely withholding irrigation for 60-90 days (until full dormancy/leaf firing is achieved). A completely randomized experimental design will be used with two factors (genotype and irrigation treatment) with three replications. Two irrigation treatments (well-watered/non-stressed and no irrigation/drought stress) will be used. During the 60-90 day treatment period, data will be collected for this experiment as described for objective 1. At the end of the treatment period, root growth will be evaluated in each lysimeter for all treatments and entries. Total root mass will be measured, and root length, volume, density will be analyzed using WinRhizo root scanning software (Regent Instruments, Inc., Quebec, Canada). This experiment will be completely repeated in time to obtain two full runs of the experiment in the greenhouse.All data for objectives 1-3 will be analyzed using SAS University Edition. The experimental design will be a randomized complete block design for objectives 1-2 and a completely randomized design for objective 3. Analysis of variance will be performed using PROC GLM or PROC MIXED at the 0.05 significance level. When appropriate, mean separation will be performed using Fisher's protected LSD, also at the 0.05 significance level.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:The target audience reached duringthis reportingwere turfgrass industry professionals including sod producers, seed producers, golf course managers, sports turf managers, and lawn/landscape companies; landscape and nursery managers; University extension personnel and Master Gardeners; University research personnel; Governmental, city, municipal, and state decision-makers; Homeowners and the general public; University teaching personnel, undergraduate and graduate students; and Oklahomans including Native American leaders and citizens. Changes/Problems:There were no major changes or problems for this project. There were no major problems or significant deviations from the research goals and objectives. There were no unexpected outcomes or changes in protocols. What opportunities for training and professional development has the project provided?This project has trained one research associate, one agronomist, one post-doctoral researcher, one Extension Assistant, one MS graduate student, one Ph.D. graduate student, and 10 undergraduate students in aspects of turfgrass science and management related to warm-season turfgrass abiotic stress tolerance. In addition, this project has provided professional turfgrass and horticultural industry training to over 400 participants in 2019-2020. How have the results been disseminated to communities of interest?The results of this project have been disseminated through publication of peer-reviewed manuscripts, scientific conference presentations and papers;University Extension guides, fact sheets, bulletins, and current reports;turfgrass and landscape industry trade and magazine articles;television segments on Oklahoma Gardening and local news channels;two University turfgrass program websites;newspaper articles;Horticultural tips articles;and various workshops, field days, classes, and presentations. What do you plan to do during the next reporting period to accomplish the goals?This upcoming year will be the second year of this project. I plan to continue to complete these projects, collect and analyze data, and publish and disseminate results in the second year of this project (2020-2021).

Impacts
What was accomplished under these goals? Twenty entries from four warm-season grass species were evaluated for drought response and irrigation requirements in 2019-2020. These entries were established and evaluated under a rainout, drought shelter in Perkins, OK. Plots were irrigated to prevent stress through the spring of 2020, then watering ceased for 65 days through the summer. Data wascollected to determine the volume of irrigation water applied to each plot to maintain acceptable turf quality. There was a difference in irrigation requirements among and within species. All plots were rewatered after 65 days and the drought simulation will be repeated through 2022. In another field trial, several entries from four warm-season grass species were established under a field rainout, drought shelter in 2020. These entries will be evaluated under simulated drought conditions during the 2021 - 2023 growing seasons. These entries were collected from turfgrass breeders at Oklahoma State University, Texas A&M University, the University of Georgia, the University of Florida, and North Carolina State University. Thus far, establishment rate data has been collected in 2020. Greenhouse pots were established in 2020 to evaluate the morphological and physiological response of bermudagrass genotypes exposed to dehydration stress under a controlled environment. These bermudagrass entries were collected from turfgrass breeders at Oklahoma State University andthe University of Georgia. A graduate student has been hired for Spring 2021 and this work will begin in 2021 and will go through 2023. Several bermudagrass genotypes from Oklahoma State University were tested for cold temperature and freezing stress in 2019-2020. The LT50 (the lethal temperature at which there is 50% survival) for each genotype was determined. This work was completed with assistance from a Ph.D. student at Oklahoma State University. This work is being submitted for publication in HortScience in 2021. A study was completed to evaluate differences in root growth among bermudagrass experimental genotypes and industry-standard cultivars in 2019-2020. There were differences in rooting characteristics among the genotypes studied. This work was presented by an Oklahoma State University MS student at the Agronomy, Crops, Soils Annual International Conference in 2020 through the ASA, CSSA, SSSA. The student presentation was awarded second place in the graduate student poster competition for the C-5 division.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Gouveia, B.T., E.F. Rios, J.A. Rodrigues Nunes, S.A. Gezan, P.R. Munoz, K.E. Kenworthy, J.B. Unruh, G.L. Miller, S.R. Milla-Lewis, B.M. Schwartz, P.L. Raymer, A Chandra, B.G. Wherley, Y. Wu, D.L. Martin, and J.Q. Moss. 2020. Genotype-by-environment interaction for turfgrass quality in bermudagrass across the southeastern United States. Crop Science 60:3328-3343. http://dx.doi.org/10.1002/csc2.20260
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Fang, T., H. Dong, S. Yu, J.Q. Moss, C. Fontanier, D. Martin, J. Fu, and Y. Wu. 2020. Sequence-based genetic mapping of Cynodon dactylon Pers. reveals new insights into genome evolution in Poaceae. Communications Biology 3, 358. https://doi.org/10.1038/s42003-020-1086-y
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Fontanier, C., K. Su, L. Gopinath, Y. Wu, C. Goad, and J.Q. Moss*. 2020. Lipid composition of three bermudagrasses in response to chilling stress. Journal of the American Society for Horticultural Science. 145:95-103. https://doi.org/10.21273/JASHS04815-19
• Type: Other Status: Published Year Published: 2020 Citation: Anella, L., D. Hillock, and M. Schnelle. 2020. Oklahoma proven: plant selections for Oklahoma. Editors: K. Moore and J.Q. Moss. Oklahoma Cooperative Extension Service Publication E-1052.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Kaur, C, J.Q. Moss, Y. Wu. and D.L. Martin. 2020. Differences in rooting characteristics of bermudagrass cultivars and OSU experimental genotypes. 2020 ASA-CSSA-SSSA International Annual Meeting. Virtual/Online.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Yu, S., Y. Wu, C. Fontanier, D. Martin, J.Q. Moss, and L. Yan. 2020. Genetic variability and QTL mapping of morphological and adaptive traits in African bermudagrass. 2020 ASA-CSSA-SSSA International Annual Meeting. Virtual/Online.
• Type: Other Status: Published Year Published: 2020 Citation: Biswell, J, C. Cook, J. Daniels, D. Harris, B. Joliff, D. Lindemann, N. Neal, D. ONeil, D. Mills, J.Q. Moss, C. Osborne, J. Vogel, J. Walker, and C. Wise. 2020. Oklahoma Golf Industry Best Management Practices. Oklahoma Golf Course Superintendents Association, Stillwater, OK and Golf Course Superintendents Association of America, Lawrence, KS.