RPR® - Regenerating Perennial Ryegrass

Barenbrug’s innovative research and development has produced a new star; a tough perennial ryegrass technology, Regenerating Perennial Ryegrass, or RPR.  A spreading, stoloniferous perennial ryegrass, RPR outperforms traditional perennial ryegrass. It’s more resilient and tolerant of difficult warm, humid summers. Chosen for sports venues, golf, and municipal uses and greenbelts,  it could be an ideal choice for your sports field, golf course, lawn or landscape.


Exhaustive Research – Remarkable Results 

It is RPR’s regenerating ability and extreme traffic tolerance that separates it from traditional perennial ryegrass. A product of advanced conventional breeding techniques, RPR plants develop determinate-stolons, which allow them to regenerate in all compass directions. Determinate stolons arise from an auxiliary bud near the base of the mother plant and then grow horizontally at, or just below, the surface of the ground, creating identical new plants as they grow. RPR plants caught the attention of our plant breeders at the Barenbrug research site in Virginia. At this locations, new grasses are developed for wear, drought, and tolerance to cold and summer extremes. Researchers noticed that RPR was thriving under tough conditions, expanding even in high stress areas, for example, where the tractor made turns at the ends of rows towing the wear simulator equipment. Next, RPR was tested at Barenbrug’s research fields near Albany, Oregon. Using 'space planted' RPR plants, our turfgrass breeders studied the lateral growth of RPR under frequent mowing. Below, the graph shows how RPR spreads compared to an average perennial ryegrass plant.

Barenbrug's RPR spread more than traditional perennial ryegrass

At left, traditional perennial ryegrass. At right, RPR after one year.


Circumference Of Space Plants

Notice in the graph below how, on two recording dates, RPR was much larger than a typical perennial ryegrass. At the later date, the circumference of the RPR plant was 33 inches compared to perennial ryegrass, measuring 24 inches. The difference gives a 25 percent edge to RPR. Within a year, the RPR plants were well rooted and had spread to three feet wide. Barenbrug extensively tests all of its varieties and RPR is no exception. It has exceeded the company’s most stringent quality requirements for traffic tolerance, wear recovery, drought tolerance and turf quality.

RPR spread 26.5 inches in the first year and 33.2 in the second, compared to 22 and 24.6 inches of normal perennial ryegrass

Determinate stolons

Determinate stolons, sometimes called “runners,” are growth shoots emerging from auxiliary buds at the base of each plant. When an RPR plant gets room, say, when a divot is removed or the turf is otherwise damaged, determinate-stolons will grow horizontally into the empty area and develop roots at its internodes. See the photos to the right, showing RPR plants, determinate stolons and the developed roots.

RPR stolons shoot whenever there is room

The pictures above show determinate stolons rooting down in RPR.



The Ohio State University researchers did a determinate stolon count comparing RPR and a traditional perennial ryegrass blend. The study was done on turf plots with both 50% ground cover and 100% ground cover. The bar to the right shows that even high quality perennial ryegrasses do not produce determinate stolons, whereas about 11% of the RPR plants do grow determinate stolons, which generate new plants.


 Even high quality perennial ryegrasses do not produce stolons, whereas 11% of RPR does



RPR Exhibits Unrivaled Wear Tolerance

RPR performance has been tested intensively at different research universities where it was analyzed for fundamental characteristics including wear tolerance. The results: RPR is vastly superior on wear tolerance compared to any other perennial ryegrass. The turf quality also remains high, even under the heavy wear. At The Ohio State University, research plots were rigorously subjected to artificial traffic. In the graph to the left, you can see the dramatic increase in tolerance from RPR. Likewise, RPR was tested for wear tolerance at the Southeastern Turfgrass Research Center, Lexington, Kentucky. As in The Ohio State University study, the results show RPR a clear winner against other perennial ryegrass.


Barenbrug agronomists also tested RPR for turf quality at several sites in the US. The graph to the right shows the turf quality of RPR compared with regular perennial ryegrass. The data was gathered at the Southeastern Turfgrass Research site in the fall, when grasses are under more stress. Look at how RPR sustains its high quality turf rating.


RPR had a higher turf quality rating after intense traffic than a ryegrass blend

Naming RPR Varieties

As with most Barenbrug turfgrass varieties, RPR varieties will all feature the traditional BAR prefix. The three currently named RPR varieties are associated with the Greek alphabet. The first two varieties are Baralpha and Barbeta, with the latest variety named Bargamma. The RPR improvement program is continuing with a new introduction to be released in the next few years.



RPR Blends And Mixtures 

Perennial ryegrass is often used by itself but also mixes well with other species. Likewise, RPR can be purchased and used by itself, Turf Star RPR,  or in various mixtures, for example, with Kentucky bluegrass.. For more information, contact Barenbrug or your local Barenbrug distributor.



RPR Maintenance

The recommended seeding rate of RPR is 300 lbs. per acre, or about 7 lbs. per 1,000 sq. ft. While RPR has been tested at several mowing heights, Barenbrug recommends a cutting height of 1.5 inches for best performance. For golf and sports turf venues, RPR varieties will tolerate mowing heights as low as 0.5 inch. Annual fertility rates are comparable to regular perennial ryegrass. Endophyte-enhanced, RPR exhibits strong heat tolerance during warm summers and conditions of moderate drought.


RPR stands up to heavy traffic, making it ideal for sports turf.

RPR stands up to heavy traffic and wear while keeping its good looks.


Benefits Of RPR Regenerating Perennial Ryegrass

  • Perennial ryegrass with determinate stolons
  • New turf sub-species, Lolium perenne ssp. stoloniferum. 
  • Completely unique to the Turf Industry
  • Developed through a process of intense traffic simulation
  • Superior traffic tolerance to other perennial ryegrasses
  • Dark green color / Lower growing / Uniform, fine-leaved texture
  • Endophyte-enhanced for superior summer performance
  • Increased disease resistance
  • Increased insect tolerance
  • Outstanding performance for sports turf, golf, park and recreational fields, commercial, and residential turf