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Registration of RTx437 sorghum parental line. (Parental Line).

RTx437, a sorghum [Sorghum bicolor (L.) Moench] parental line (Reg.no. 282, PI 629034), was developed and released by the Sorghum Improvement Program of the Texas Agricultural Experiment Station at College Station, TX. This line is suitable for use as a male parent in the production of hybrids with good grain quality and/or as germplasm for use in a breeding program that emphasizes agronomic and grain quality improvement. In hybrid combinations, this line has produced white-grain tan plant hybrids with consistently high yields. The hybrids also have good agronomic and grain quality characteristics.

RTx437 was developed using pedigree breeding methodology and has a pedigree of (77CS4 x RTx430)-B1-B2-B1-B1-B4-B1-CBK. 77CS4 is an unreleased line in the sorghum breeding program which was a selection from the partially converted version of SC120-14E (IS 2816C)(Rosenow et al., 1997). IS 2816C is a white, tan zerazera (Murty and Govil, 1967) from Sudan that was converted and released by the TAES/USDA in 1970 (Rosenow et al., 1997). RTx430 was developed and released in 1976 by the Texas Agricultural Experiment Station (Miller, 1984). The initial [F.sub.1] was made in a greenhouse in College Station by hand emasculation. [F.sub.2] progeny were selected at College Station, TX. Selections in the [F.sub.3] through [F.sub.8] generations were made at Beeville or Corpus Christi, TX. In most generations, selections were made in nurseries that were rainfed, and encountered significant disease pressure. Final selection and initial increases of RTx437 were made at College Station in 1990.

Grain from RTx437 has a white pericarp (rrYY), thick mesocarp (zz), and no testa ([b.sub.1][b.sub.1][B.sub.2][B.sub.2]). The line has tan plant color (ppqq), light brown glume color, and is awnless (AA). The line has moderate resistance to insecticide phytotoxicity, but the reaction is difficult to detect because of the tan plant color. The panicles are semicompact, glumes cover approximately 20% of the seed, and the grain is easily threshed from the panicle. Seed and/or grain of RTx437 are medium in size. Thousand seed weight of RTx437 averaged 27.6 g over four environments. RTx437 fully restores fertility in the A1 cytolasmic sterility system, but it is does not restore fertility to the A2 and A3 cytoplasmic sterility system.

Days to 50% anthesis for RTx437 range from 58 to 90 d (Table 1). RTx437 is genetically a three dwarf inbred (d[w.sub.1]D[w.sub.2] d[w.sub.3]d[w.sub.4]) in plant height, and phenotypically, the plant height of RTx437 ranges from 79 to 115 cm (Table 1). Panicle exsertion of RTx437 ranged from 0 to 17 cm (Table 1). Leaf and plant death ratings for RTx437 are similar to those of RTx436 (Miller et al., 1992), RTx430 and Tx2783 (Peterson et al., 1984), but the line will express higher levels of stress susceptibility than the checks under extremely dry conditions. On average, desirability ratings for RTx437 were similar to ratings for RTx430, RTx436, and Tx2783 (Table 1).

RTx437 is resistant to systemic and local lesion downy mildew pathotype 1 infection [caused by Peronosclerospora sorghi (W.Weston & Uppal) C.G. Shaw]. RTx437 is resistant to head smut [caused by Sporisorium reilianum (Kuhn) Langdon & Fullerton]. RTx437 shows moderate tolerance to Maize dwarf mosaic virus (MDMV) and it is susceptible to anthracnose [caused by Colletotrichum graminicola (Ces.) G.W. Wilson] when evaluated in College Station, TX. RTx437 is susceptible to grain mold, but has moderate levels of resistance to rust (caused by Puccinia purpurea Cooke), and zonate leaf spot (caused by Gloeocercospora sorghi D. Bain & Edgerton). The line has not been evaluted for reaction to any insect pests.

In hybrid combinations, RTx437 has good general combining ability. Hybrids of RTx437 with three different inbred lines in over 30 environments yielded 110% of RTx436 hybrids with the same females. Grain quality parameters for hybrids of RTx437 are similar to those of RTx436 hybrids. Performance of RTx437 hybrids was consistent across a wide range of environments, and there was no specific environment in which RTx437 hybrids performed consistently better or worse than the checks.

Seed of RTx437 will be maintained by the Dep. of Soil & Crop Sciences, Texas A&M University, College Station, TX 77843-2474. Small samples of RTx437 are available for distribution upon written request to the corresponding author. We request that appropriate recognition of the source be given if this germplasm contributes to the development of new germplasms or parental lines.
Table 1. Agronomic characteristics of RTx437 and checks from a
total of 16 environments across Texas and Kansas.

            Days to 50%
             anthesis     Plant height

Genotype   Mean   Range   Mean    Range

                           cm      cm

RTx437      71    58-90   102    79-119
RTx436      73    57-90   106    86-125
Tx2783      77    64-99   106    84-117
RTx430      72    60-90   109    86-124

                          Desirability
             Exsertion     ([dagger])

Genotype   Mean   Range   Mean    Range

            cm     cm

RTx437      7     0-17    2.8    1.4-3.5
RTx436      7     0-17    2.8    1.3-3.7
Tx2783      1     0-3     3.0    1.3-4.4
RTx430      3     0-10    2.9    1.4-4.1

([dagger]) Desirability ratings are a subjective
rating based on a scale of 1 (best) to 10 (worst).


Acknowledgments

This research was supported in part by the International Sorghum/Millet Collaborative Research Support Program (INTSORMIL), which is funded by the United States Agency for International Development (USAID), and the Texas Grain Sorghum Producers Board. We acknowledge the support of the Sorghum Improvement Program staff involved in testing these lines.

References

Miller, F.R. 1984. Registration of RTx430 sorghum parental line. Crop Sci. 24:1224.

Miller, F.R., T.F. Dusek, K.L. Prihoda, and L.W. Rooney. 1992. Registration of RTx436 sorghum parental line. Crop Sci. 32:1518.

Murty, B.R., and J.N. Govil. 1967. Description of 70 groups in genus Sorghum based on a modified Snowden's classification. Indian J. Gen. Plant Breed. 27:75-90.

Peterson, G.C., J.W. Johnson, G.L. Teetes, D.T. Rosenow, and R.E. Schaffert. 1984. Registration of Tx2783 greenbug resistant soghum germplasm line. Crop Sci. 24:390.

Rosenow, D.T., J.A. Dahlberg, G.C. Peterson, L.E. Clark, F.R. Miller, A. Sotomayor-Rios, A.J. Hamburger, P. Madera-Torres, A. Quiles-Belen, and C.A. Woodfin. 1997. Registration of fifty converted sorghums from the sorghum conversion program. Crop Sci. 37: 1397-1398.

W.L. ROONEY, * F.R. MILLER, AND L.W. ROONEY

W.L. Rooney and L.W. Rooney, Associate Professor and Professor, respectively, Dep. of Soil & Crop Sciences, Texas A&M University, College Station, TX 77843-2474; F.R. Miller, Professor (retired), Dep. of Soil & Crop Sciences, Texas A&M University, College Station, TX 77843-2474; Registration by CSSA. Accepted 31 July 2002. * Corresponding author (wlr@tamu.edu)
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Author:Rooney, W.L.; Miller, F.R.; Rooney, L.W.
Publication:Crop Science
Date:Jan 1, 2003
Words:1115
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