Arkansas Agricultural Experiment Station, University of Arkansas Division of Agriculture
Dale Bumpers College of Agricultural, Food and Life Sciences

A newsletter for faculty, staff and students

July-August 2005 • Vol. 31, No. 4

Notice of Release of Arkot 9203-03 and Arkot 9203-17 Germplasm Lines of Cotton

The Arkansas Agricultural Experiment Station announces the release of two noncommercial breeding lines of cotton, Gossypium hirsutum L., designated Arkot 9203-03 and Arkot 9203-17.   The two sister lines, developed using the generalized procedures outlined by Bourland (2004), were derived from a 1992 cross between ‘H-1330’ (Bourland, 1996) and ‘Delcot 344’ (Sappenfield, 1987).  Within F2 populations grown at Southeast Branch Station at Rohwer, AR, in 1993, bolls from visually superior individual plants were harvested and bulked.  Plants derived from F3 seeds were selected using modified proce­dures of Bird (1982) to produce seeds for F4 progeny rows grown in 1995.   Progenies designated as 9203-03 and 9203-17 were among the ones promoted and tested in replicated strain tests in 1996 and 1997.  Individual plant selections from the F6 generation of these two strains were evaluated as progenies in 1997.  Two of these selections produced Arkot 9203-03 (tested as 9203-03-20) and Arkot 9203-17 (tested as 9203-17-12).  

The two lines were included in 18 replicated field tests at four Arkansas Agricultural Research Station sites in the Mississippi River Delta and compared to ‘SG 747' in 2001,  ‘SG 105' in 2002-2003, and ‘DP 444 BG/RR’ in 2004.  Over all tests, lint yields of Arkot 9203-03 were 10% greater than the checks, and were significantly higher than the check cultivar in 9 of the 18 tests.  The increased yield of the line appeared to be associated with producing more seed per area and a higher number of fibers per seed than the check cultivars.  Yields of Arkot 9203-17 were essentially equal to the check cultivars in the 18 Arkansas tests, but exceeded ‘SG105’ and Arkot 9203-03 in tests at Tifton, GA, in 2002 and 2003. 

Compared to the check cultivars, fibers of both lines tended to be finer (lower micronaire) and stronger, but had lower elongation than the check cultivars.   Fibers of Arkot 9203-17 were longer and stronger than the check cultivars and Arkot 9203-03. 

The two lines were taller than the check cultivars with Arkot 9203-03 being taller than Arkot 9203-17 (Table 1).  Although taller than the check cultivars, open boll ratings in 2003 and 2004 indicated that the lines were as early or earlier maturing than the check cultivars (Table 3).  Over six tests, leaf pubescence of Arkot 9203-03 and Arkot 9203-17 averaged 4.4 based on a rating scale of 1 (smooth leaf) to 7 (very hairy) (Bourland et al., 2003).

Arkot 9203-03 and Arkot 9203-17 display good host plant resistance traits. During selection, both lines were screened for resistance to races 1, 2, 7, and 18 of Xanthomonas campestris pv. malvacearum (Smith) Dye, the causal agent of bacterial blight.  Resistance to these races conveys resistance to all known U.S. races of this pathogen.  In subsequent tests, neither line exhibited symptoms of bacterial blight even after field inoculations with the pathogen.  Wilted plants associated with Verticillium wilt (caused by Verticillium dahliae, Kleb.) of both lines exceeded SG 105 in a 2002 field test, but were equal to DP 444BR/RR in 2004.   In the 2004 National Cotton Fusarium Wilt Test at Tallassee, AL, resistance levels of both Arkot 9203-03 and Arkot 9203-17 to fusarium wilt [caused by Fusarium oxysporum Schlect. F. sp. vasinfectum (Atk.) Snyd. & Hans.] were equal to the resistant check (Glass et al., 2004).  In 2003, both lines were more resistant to tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)) than the susceptible frego-bract check, but Arkot 9203-17 had significantly more damaged flowers than SG 105.    

Arkot 9203-03 had the second highest yield of 19 lines evaluated in the 2003 Regional Breeders’ Network Test (Table 4).  These data suggest that the line has wide adaptation.  Over the eight locations, Arkot 9203-03 had significantly higher lint percent, larger bolls, and lower fiber strength, elongation and micronaire than PSC 355.  (Arkot 9203-17 was not evaluated in this test.)

The combinations of yield adaptation, fiber properties, and specific host plant resistance traits of these lines make the lines valuable to cotton breeding programs.  Arkot 9203-03 appears have superior yielding ability but lower fiber quality than Arkot 9203-17.  Development of the two lines was supported in part by funding from Cotton Incorporated.  Small quantities of Arkot 9203-03 and Arkot 9203-17 seed may be obtained for breeding purposes from F.M. Bourland, P.O. Box 48, Northeast Research and Extension Center, Keiser, AR 72351.  Unless specifically approved by the Arkansas Agricultural Experiment Station, the lines may not be used as recurrent parents in a breeding program.

                                                             References

Bird, L.S.  1982.  The MAR (Multi-Adversity Resistance) system for genetic improvement of cotton. Plant Dis. 66:172-176.

Bourland, F.M.  1996.  Registration of ‘H1330' cotton.  Crop Sci.  36:813.

Bourland, F. M.  2004.  Overview of the University of Arkansas cotton breeding program.  pp. 1093-1097.  In Proc. Beltwide Cotton Conf., San Antonio, TX.  5-9 Jan. 2004.  Natl. Cotton Counc. Am., Memphis, TN.

Bourland, F. M., J. M. Hornbeck, A. B. McFall, and, S. D. Calhoun.  2003.  A rating system for leaf pubescence of cotton.  J. Cotton Sci. 7:8-15.

Glass, K.M., W.S. Gazaway, and E. van Santen.  2004.  2004 National cotton fusarium wilt report.  Agronomy and Soils Department Series No. 262.  Auburn University, Auburn, AL.

Sappenfield, W. P.  1987.  Registration of ‘Delcot 344’ cotton.  Crop Sci. 27:150.