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Genetic Advance in New Multi-Adversity Resistance (MAR) Cotton Germplasm

P.M. Thaxton, K.M. El-Zik


The main emphasis of the Multi-Adversity Resistant (MAR) program is to develop improved cotton germplasm and varieties for the Southwest USA cotton belt. New MAR-7A and MAR-7B strains were extensively tested in 1994 and 1995 in the Early Field Planting Test (EFP) at four locations and the Uniform MAR test (UMAR) at 10 locations. New strains with higher levels of resistance to insects and pathogens than previously released MAR germplasm have been identified. The advanced MAR-7 strains gave high stands under the exceptional cold and wet conditions following planting in 1995, indicating high resistance to seed-seedling pathogens and cold tolerance. Resistance levels were improved for pathogens causing Phymatotrichum root rot, Verticillium and Fusarium wilts.

Average lint yield for MAR-7A strains over nine UMAR tests was 592 lb/acre, with a range among locations from 279 lb/acre for McGregor to 926 lb/acre for the Brazos Valley test. In the EFP tests averaged over four locations, yield for the MAR-7B strains ranged from 427 lb/acre at College Station to 739 lb/acre at the Corpus Christi test, with a mean of 636 lb/acre. The MAR-7 germplasm is genetically diverse for many agronomic and morphological traits. The 1995 results continue to document the improvement in fiber quality traits in the MAR germplasm. Fiber quality traits have improved in the MAR-7 strains, with fiber length ranging from 1.10 to 1.25 inches, uniformity 83.3 to 86.5, strength 28.5 to 34.2 g/tex, elongation 5.5 to 6.9, micronaire 3.7 to 4.8, maturity 80.6% to 95.1% and fineness 149 to 178.

Based on extensive testing and data base we have identified and selected superior cotton strains. Several advanced MAR-7A strains will be released in early 1997. Also, possibly a smooth (glabrous) MAR Tamcot variety will be released in 1997. Advanced MAR-7A strains that combine the many desired traits are: CBD3CUBPIH-3-91, CUBQHGRPIS-1-92, CUBQHGRPIH-1-92, CDRCIQCUBH-2-92, CDULBQSHPS-1-93, BLCGG8CP45H-1-93, and PD23CD3HGS-1-93. The MAR-7B strains will be further tested to determine their stability over Texas Cotton growing regions and will be released in two years. The MAR-7B promising strains are HGPIHQBPIH-2-94, HGPICG14QH-1-94, PD24HQBPIH-1-94, SPNXHQBPIS-1-94, and HGPICDHGBS-1-94. The new MAR-7 releases will maximize sustainable profits to growers and benefit the USA cotton industry.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 601 - 611
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998