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Simplot/Jacklin Seed, West 5300 Riverbend Ave., Post Falls, ID 83854-9499
* Corresponding author (dbrede{at}simplot.com)
‘Rambo’ Kentucky bluegrass (Poa pratensis L.) (Reg. no. CV-70, PI 610205) is a turf-type cultivar released in August 1998, by the J.R. Simplot Co., Jacklin Seed, Post Falls, ID. Experimental designations for Rambo were 92-2579 and J-2579.
Rambo originated from a highly apomictic, single-plant selection from an open-pollinated cross in the Jacklin Seed, Post Falls breeding nurseries. The parentage of Rambo traces to breeding line 90-0499, which originated from a naturally occurring hybrid from ‘Midnight’ Kentucky bluegrass (Meyer et al., 1984). Breeding line 90-0499 was selected from a Post Falls nursery on 9 July 1990. It produced a moderately open turf with little or no ergot [Claviceps purpurea (Fr.) Tul.] in seed production. In June 1991, a plant of 90-0499 was hybridized with pollen from 20 other Kentucky bluegrasses, and the progeny were planted in a spaced-plant field nursery of 400 plants in July 1991. Offspring with characteristics dissimilar to 90-0499 were flagged during maturation in 1992. Plant number 92-2579 differed from 90-0499 for vegetative plant characteristics before seedhead expression. Reproductive characteristics of 92-2579 showed similarity to ‘Limousine’ Kentucky bluegrass (Alderson and Sharp, 1994). Seed harvested from 92-2579 was used to establish a turf trial in September 1992, a replicated seed yield trial in August 1993, and a U.S. Plant Variety Protection trial in June 1995, near Post Falls.
Rambo most closely resembles Midnight for seed production but differs from it for seven characters detailed in the U.S. Plant Variety Protection application for Rambo. The panicles are most similar in appearance to those of ‘NuGlade’ (Brede, 2001) but are more brownish-yellow in color. The culms are slightly taller than NuGlade, and the leaves during seed production are lighter green.
The apomixis rate of Rambo averages 90%. Most of the variants are "common-type" in appearance, averaging 1 m in culm length, with susceptibility to leaf spot [caused by Drechslera poae (Baudys) Shoem]. Other variants include a lower-growing Limousine-type plant and a taller-growing, earlier maturing, lighter green plant that resembles 90-0499.
Rambo ranked 27th out of 103 entries for turf quality in the final summary of the 1995 National Turfgrass Evaluation Program (NTEP) trials for Kentucky bluegrass (Morris, 2001). Rambo ranked among the top 10 entries for turf quality in trial locations in Massachusetts, Maryland, Missouri, and Nebraska. Rambo showed good resistance to stem rust disease (caused by Puccinia graminis Pers.:Pers.), summer patch (caused by Magnaporthe poae Landschoot and Jackson), powdery mildew (caused by Erysiphe graminis DC. ex Merat), and moderate resistance to leaf spot. Rambo exhibits high shoot density throughout the year. In NTEP tests, it ranked 4th in spring density, 6th in summer density, and 4th in fall turf density, out of 103 entries. In 6 yr of commercial seed production, Rambo has demonstrated the potential for high yields of quality seed, relative freedom from ergot, and no adverse reactions to labeled Kentucky bluegrass pesticides.
Rambo is recommended for golf course tees, fairways, and roughs, and for lawns, parks, and sports turf, in full sun or some shade, in areas where Kentucky bluegrass is well adapted for turf. It is compatible in blends and mixtures with other cool-season turfgrasses at mowing heights as low as 13 mm.
Breeder seed, first harvested in 1996, is maintained by Simplot/Jacklin Seed. Seed propagation is limited to one generation of increase for Foundation, Registered, and Certified seed. U.S. Plant Variety Protection application no. 9900408 has been filed for Rambo.
NOTES
Accepted for publication December 31, 2002.
REFERENCES
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