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a Texas A&M Univ. Agric. REC, P.O. Box 200, Overton, TX 75684
b Texas A&M Univ. Agric. REC, 1509 Aggie Dr., Beaumont, TX 77713-9185
* Corresponding author (lr-nelson{at}tamu.edu).
‘TAMTBO’ (Reg. No. CV-249, PI 644087) Italian ryegrass (Lolium multiflorum Lam.) was developed by the Texas Agricultural Experiment Station (TAES) as a cool-season forage grass. TAMTBO is a tetraploid where 4n = 4x = 28 chromosomes. The predominant use is projected to be in overseeding warm season pastures for winter production of forage for grazing animals. TAMTBO is improved for forage yield potential compared to most cultivars presently being grown in East Texas. It was tested under the experimental designation as TXR2005-TBO and released by TAES in 2006.
TAMTBO is a top-cross from ryegrass breeding lines TXR2000-T2, TXR2002-T17, and the cultivar Jumbo. Jumbo (Prine et al., 2002) is a tetraploid cultivar released by the University of Florida. Both of the above TAES lines were derived from germplasm of ‘TAM 90’ (Nelson et al., 1992), which had been treated with colchicine to double the chromosome number from 14 to 28. TXR2000-T2 had been selected (high forage potential) in a space planted nursery at Overton in 1997–1998. Seed from selected plants was bulked, and that seed was increased in Oregon in 1998–1999 and was designated TXR2000-T2. TXR2002-T17 was space planted at Overton in 1997–1998. In 1998–1999 it was again space planted at Overton, and seed from selected plants demonstrating high tillering, large plants, and wide leaves were bulked and designated TXR2002-T17.
The top-cross was made by growing adjacent rows of TXR2000-T2, TXR2002-T17, and Jumbo. Any plants not exhibiting good forage potential (large plants with wide leaves and high tiller number) were removed from the population before cross-pollinating. Seed was harvested from individual plants and bulked. In 2002–2003 this seed was grown in a space planting (500 plants) at Beaumont, TX. Thirty-four plants exhibiting high forage yield potential and crown rust resistance (incited by Puccinia coronata Corda) where plants showed no disease were allowed to cross-pollinate and produce seed, and seed was bulked. In 2003–2004 this seed was increased in Oregon by OreGro Seeds, Inc. (Albany, OR). This seed was returned to Overton and designated TXR2005-TBO.
TAMTBO is a tetraploid forage-type annual ryegrass and should be considered an Italian-type annual ryegrass. It has a large plant stature compared with diploid cultivars. In seedling stage, 95% of coleoptiles have anthocyanin. Growth habit is upright. Plant stature of TAMTBO was 116 cm, larger and taller (P > 0.01) than ‘Gulf’ (Weihing, 1963) but similar to TAM 90, which is larger than most diploid cultivars. TAMTBO averaged about 10 cm less in mature plant height compared with Jumbo and ‘Prine’ (two tetraploid cultivars) in space plantings at Overton. Flag leaf length of TAMTBO was 15.3 cm and was slightly longer than other cultivars, which were 13.2, 11.7, and 13.8 for Gulf, TAM 90, and Jumbo, respectively. Leaf width was 10.6 mm for TAMTBO, not different than Jumbo and Prine but about 1 mm wider than TAM 90 and 2 mm wider than Gulf. In space plantings at Overton, TAMTBO produced an average of 46 tillers per plant compared with 57, 61, 49, and 40 for TAM 90, Gulf, Jumbo, and Prine, respectively. Spike length for TAMTBO was 24 cm, which was not different from other cultivars. Number of spikelets per spike for TAMTBO was 32, which was the same as Jumbo and Prine; however, TAM 90, and Gulf had 29 and 26, respectively. Mean awn length of TAMTBO was 7 mm, which was similar to Gulf and TAM 90 but about 1 mm less than Prine or Jumbo. Freeze damage has not been observed on TAMTBO over the past 3 yr at Overton when a low temperature of –8 °C occurred. However, no freeze injury occurred on any cultivars at this temperature. TAMTBO is not infected with the fungal endophyte (Moon et al., 2000). The fluorescence level of TAMTBO according to the Oregon State Seed Testing Laboratory was 100%. They also reported that TAMTBO was 100% tetraploid.
In forage clipping trials at Overton, TX, during the 2004–2005 and 2005–2006 growing seasons (Table 1 ), TAMTBO had higher forage yields than any commercial cultivar, but it was not significantly better than Jumbo either year. In forage trials at Beaumont, TX, in 2005–2006, TAMTBO produced average forage yields; however, it was not significantly different than Jumbo or Prine. TAMTBO has produced above average forage yields in Mississippi and Georgia over the past 2 yr.
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Uses of TAMTBO will be for overseeding warm-season forage species such as bermudagrass [Cynodon dactylon (L.) Pers.]. It can also be planted into a prepared seedbed and planted with small grains such as wheat (Triticum aestivum L.), rye (Secale cereal L.), or oat (Avena sativa L.). Range of adaptation for cool-season planting will be in the lower south of the USA or as temporary forage during the summer in the northern USA. Seed production will be in Oregon. Breeder seed of TAMTBO will be maintained by TAES. OreGro Seeds, Inc., has an exclusive license for production of a licensed cultivar as Foundation class seed stock and to produce and sell TAMTBO as a licensed product. U.S. Plant Variety Protection will be filed for TAMTBO. All seed requests should be sent to the corresponding author during the period of protection by the Plant Variety Protection Certificate. Seed of this release is deposited in the National Plant Germplasm System, where it will be available after the expiry of the Plant Variety Protection for research purposes, including development and commercialization of new cultivars. It is requested that appropriate recognition be made if the cultivar contributes to the development of new germplasm or cultivars.
Footnotes
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication March 7, 2007.
References
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