The focus of the visit to one of the TWCA’s testing sites, NexGen in Albany Oregon, was on drought stress and drought resistance work being conducted within species and the differences in varietal reactions to drought situations. The presentation was split into three parts 1) Digital Image Analysis (DIA), 2) Drought Stress (Chronic vs. Acute), and the efforts of 3) Turfgrass Water Conservation AllianceM (TWCA).
DIA. The purpose and method of using digital images is to rate green cover of a given plot of turf thereby removing subjective ratings. The light box, designed to create consistent lighting and distance from the grass that is unchanging, is placed over each turf plot and digital photos are taken. These digital images are then analyzed by computer to determine the amount of green pixels in each photo, removing subjectivity, said presenter and researcher Tami Brown. This has enabled researchers to determine the exact number of days it takes for a variety to reach 25% green cover without water as well as measuring recovery time. This objective data can be compared across cultivars and across species to clearly identify varieties that are truly drought tolerant.
Drought Stress Trials (Chronic vs. Acute) – drought studies at NexGen Research Facility began in 1993 in an attempt to quantifiably measure water usage by plants. Acute drought stress is induced from removing water to the turf. The turf plots are evaluated for the decline in percentage of green. This decline can take from two weeks to ninety days, depending on the species and the cultivar. Chronic drought stress is when water is available in limited amounts to maintain the grasses at 50% green cover. Each plot is given a ½ inch equivalent of water each time the plot is below the 50% green cover. The water amounts are totaled for each plot after 90 days. This technique quantifies the water usage for each cultivar and can be directly compared to another cultivar for water savings.
Rain-Out shelters are utilized to control the amount of water a trial receives so cultivars may be evaluated for their drought tolerance. These structures utilize a greenhouse frame with removable sides to increase air movement. Drain tiles and a special draining system have been added to ensure that no moisture could move in from the surrounding area. Overhead sprinklers were placed for even water distribution. Varieties are monitored and ensured even green up and are well established prior to starting the drought.
NexGen’s studies include which varieties dry-down at the slowest rates, but also those that recover and green-up the quickest. Drought stress allows researchers to measure exactly how much water a cultivar uses before it reaches 40% green cover, and exactly how much water is used in the recovery process. When identifying drought tolerance with fewer inputs, it is important to have data that clearly shows how much water is being saved with each variety. Researcher Debra Hignight says studies have shown that the best varieties for water conservation used ½ inch of water, while the worst were using 7 inches, which is not very efficient for products that are marketed as water savers.
TWCA – Director of Research, Kenneth Hignight explained that the push for water conservation has led to the formation of the Turfgrass Water Conservation Alliance. The TWCA is a nonprofit organization dedicated to improving the environment through water conservation – namely identifying turf grass seed varieties that utilize less water so they may be specified for use by various governing bodies in public projects.
The TWCA’s current focus on drought tolerance is being conducted by several University research sites across the US, as well as NexGen’s facility in Oregon. This rigorous selection process results in a reliable list of varieties that are truly drought tolerant, with objective data to support the claim of “drought tolerant” and “water efficiency”.
Seed control officials that were a part of the tour commented on just how impressed they were with the NexGen research facility and the amazing work that they are doing there for the TWCA. Awareness of the ongoing research being conducted within turfgrass species about water conservation and other environmentally friendly traits will go far into the future.
For more information, www.tgwca.org