DEVELOPMENT OF MAR COTTON GERMPLASM WITH MORPHOLOGICAL MUTANT TRAITS
Mar 13, 2017

Breeding & Genetic improvement WCRC Breeding-Asia WCRC1
Abstract                                                                         Back to Table of contents

Higher levels of resistance to insects, plant pathogens, and abiotic stresses are needed in cotton cultivars to maintain plant health and increase yield.  The multi-adversity resistance (MAR) program has been successful in transferring and developing cotton germplasm with morphological mutant traits known to impart host resistance to pests.  Thirteen experiments were conducted over three growing seasons (1990-92) in Texas to quantify yield, earliness, and fiber quality traits of nine MAR strains with the mutant traits frego bract, nectariless, okra-shaped leaf, and red plant color.  Tests included the MAR mutant strains, advanced MAR-6 strains and cultivars representing the MAR-1 to MAR-6 gene pools.  Performance of most mutant strains was similar for all measured traits in either glabrous or hairy backgrounds.  Yields of the frego bract and nectariless strains were similar to those of non-mutant MAR-6 strains, while the okra leaf and red plant strains produced lower yields.  Nectariless and okra-shaped leaf strains were earlier in maturity, and the red plant strains matured later than MAR-6 strains.  Okra leaf strains produced a longer fiber than the other mutant strains and non-mutant cultivars.  The frego bract, okra leaf and red plant strains produced a stronger fiber compared to the Tamcot cultivars. Mutant strains generally were similar in fiber uniformity, elongation, and micronaire, but the red plant strains produced a higher micronaire value.  The MAR mutant strains have simultaneous genetic gains for many traits, and will provide new sources of host-plant resistance to cotton insects and plant pathogens.

Conclusion

The performance of the MAR cotton strains with mutant morphological traits in comparison with the new MAR-6 advanced germplasm, and the Tamcot CAB-CS and Tamcot HQ95 cultivars is summarized in Table 7.  The MAR mutant strains have the high and broad levels of resistance to insects and plant pathogens, and improved drought tolerance, as the advanced MAR-6 germplasm (El-Zik and Thaxton, 1989; El-Zik et al., 1991; Thaxton et al., 1991).  The frego bract and nectariless strains produced similar yields, and the okra leaf and red plant strains lower yields than the MAR-6 strains.  The nectariless and okra leaf strains were earlier in maturity, and the red plant strains matured later than the MAR-6 strains.  Lint percentages were lower for the red plant, okra leaf, and frego bract strains than for the MAR-6 strains and for the nectariless strains.  The okra leaf strains had a longer fiber than the other mutant strains and MAR-6 strains.  All strains generally were similar in fiber uniformity, elongation and micronaire, but the red plant strains had a higher micronaire value.  The frego bract, okra leaf, and red plant strains produced a stronger fiber than CAB-CS and HQ95, and the nectariless strains had a similar fiber strength to the Tamcot cultivars.  MAR mutants in hairy and glabrous backgrounds performed similarly for all measured traits, indicating no interaction of mutant traits with plant pubescence.

Cotton management programs of the future will depend less on pesticides to control insects and  pathogens.  Cultivars having resistance to pests will continue to be the cornerstone of crop production.  Eight new MAR cotton strains with the mutant morphological traits frego bract (fg-Sm, fg-H), nectariless (ne-Sm), okra-shaped leaf (L-Sm, L-H), and red plant color (R-Sm, R-H) are being released from the MAR program.  These MAR mutant strains have shown simultaneous genetic gains for many traits and should be useful to breeders in genetic improvement programs.  This germplasm will provide new sources of host plant resistance to insects and plant pathogens and will benefit the cotton growers and industry.

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