Registration of ‘Axcella 2’ Annual Ryegrass

L.R. Nelson and J. Crowder, Texas A&M Univ. Agric. REC, P.O. Box 200, Overton, TX 75684; D.R. Chalmers, Texas A&M Univ. at College Station, TX 77843-2474. Registration by CSSA. Received 8 Sept. 2006. *Corresponding author (lr-nelson@tamu.edu). ‘Axcella 2’ (Reg. no. CV-246, PI 642959) annual ryegrass (Lolium multifl orum Lam.) was developed by the Texas Agricultural Experiment Station (TAES) as a cool-season turfgrass for specialty uses. Axcella 2 is improved for uniformity in dwarf plant stature and for fi ner leaf texture compared to ‘Axcella’ and ‘Panterra’. The predominant use is projected to be in overseeding warm season grasses for green winter color and performance to favor a natural and smooth spring transition back to the perennial warm season grass. Axcella 2 was tested under the experimental designation of TXR2003-TF1 and released by TAES in 2006. Axcella 2 originated from the same germplasm (TXR-Dwarf) as Panterra a TAES release in 2003 (Nelson et al., 2004). In 1998–1999, 400 space plants of TXR98-DBDF (from TXR-Dwarf) were planted at Overton. Thirteen plants were selected for turf quality and were allowed to cross-pollinate in the spring and produce seed. Plants from this bulk (TXR2001-7TFL) were space planted (550 plants) in 1999–2000. All but 24 plants were eliminated from the population and the best 24 plants for turf quality were selected and allowed to produce seed. In 2000–2001, 75 out of 500 plants (TXR2002-TF3) grown at Overton were selected for green color, dwarf character, and were allowed to cross-pollinate and produce seed. In 2001–2002 nine hundred space plants from this bulk (TXR2003-TF1) were grown at Overton. Selection for dark green color, high tiller density, and uniform dwarf characteristic produced 14 plants that were transplanted to pots and allowed to cross-pollinate during the spring of 2002 and produce seed. This seed was bulked and 50 g from this population were sent to DLF-International Seed, Inc. of Halsey, Oregon. This population was grown as space plants in 2002–2003 as a seed increase. Any plants not exhibiting good turf characteristics and high seed yield potential were eliminated from the population. The seed harvested was labeled TXR2003-TF1 and is the germplasm described in this registration paper. Axcella 2 is a diploid (2n = 2x = 14). In the seedling stage, Axcella 2 has rolled leaves and no auricles. Mature plant height of Axcella 2 was 21 cm shorter (P < 0.01) than ‘Axcella’ (Nelson et al., 2001) and 14 cm shorter than Panterra and is much shorter than forage-type cultivars such as ‘TAM 90’ (Nelson et al., 1992) and ‘Gulf’ (Weihing, 1963). Spike length of Axcella 2 was 3.5 cm shorter (P < 0.01) than Panterra and 5 cm shorter than Axcella. Approximately 85% of lemmas have awns while 15% do not (awnless). Mean awn length is 3 mm. Flag leaf length of Axcella 2 was 3 cm shorter (P < 0.01) than Panterra and 5 cm shorter than Axcella. In turf trials at Overton 5 d after mowing, Axcella 2 had signifi cantly less (P < 0.05) canopy height than Axcella and Panterra. Mean tiller number on mature spaceplantings at Overton was 149 for Axcella 2, compared to 126 and 120 for Panterra and Axcella, respectively. Seed weights of Oregon grown seed were 2.1, 2.4, 2.5, and 2.8 g per 1000 seed for Axcella 2, Panterra, Axcella, and TAM 90, respectively. Seed width is approximately 1.7 mm and seed length is 6 mm. Coleoptile color on emergence may be either green or purple. Anther color is approximately 80% yellow and 20% purple. Axcella 2 is not infected with the fungal endophyte Neotyphodium occutans C.D. Moon, B. Scott, & M.J. Christensen, sp. Nov. (Moon et al., 2000). Axcella 2 tested 91% positive for fl uorescence and is similar to Axcella and Panterra in this regard. In mature plants, Axcella 2 has approximately 10% anthocyanin coloring on stems while remaining stems are green. In turf trials at Overton and College Station, turf quality ratings of Axcella 2 were similar to Panterra but superior to Axcella. Axcella 2 has fi ner textured leaves than Axcella and Panterra. It has darker green leaf color compared to Axcella. Axcella 2 is similar in color to Panterra but may hold its color longer into late spring than Panterra. Exposure to –8°C in 2005 resulted in leaf tip freeze injury but all plants recovered. Spring overseeding transition ratings, defi ned as declining percentage of green ryegrass coverage, indicated that as early as 21 April 2004, Axcella 2 decline exceeded that of perennial ryegrass (L. perenne L.). Differences became greater by 14 May when Axcella 2 stand density had declined by greater than 50%. By 28 May Axcella 2 was 96% dead. Spring transition date of Axcella 2 was not signifi cantly different than Axcella and Panterra. Data indicate that Axcella 2 transitions out about one month earlier than perennial ryegrass (‘Premier II’ was used for comparison). Published in the Journal of Plant Registrations 1:20–21 (2007). doi: 10.3198/jpr2006.09.0568crc © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA