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Tolerance of commercial Upland (Gossypium hirsutum) and Pima (G. barbadense) cotton cultivars, advanced breeding lines and glandless cotton to halosulfuron (Sandea) herbicide under field conditions

Zhang, Jinfa, Abdelraheem, Abdelraheem, Wedegaertner, Tom
Euphytica 2019 v.215 no.1 pp. 3
Gossypium barbadense, Gossypium hirsutum, analysis of variance, breeding lines, cotton, cultivars, genetic variation, genotype, halosulfuron, heritability, highlands, plant breeding, planting, screening, seedlings, weed control, weeds
Halosulfuron (Sandea) herbicide is recommended to control problem weeds with the use of hood for cotton protection. However, no information is available on genotypic variation in cotton response to Sandea. In this study, 104 entries representing 81 cotton genotypes including 8 Pima (Gossypium barbadense L.) and 73 Upland (G. hirsutum L.) genotypes were divided into four replicated tests for evaluation of Sandea tolerance at the 4–5th true-leaf stage (27 days after planting, DAP) under the same field conditions in 2016. The analysis of variance did not detect a significant genotypic difference among the Pima cotton cultivars and lines tested, while there were significant genotypic variations in the three replicated Upland cotton tests. The broad-sense heritability estimates for Sandea tolerance based on crop injury ratings at 6 days after treatment (DAT) ranged from 72.1 to 82.6%, with an average of 77.9%. When 18 lines were tested in 2–3 tests (or twice in the same test), overall consistent results in crop injury ratings were obtained, which allowed the selection of the tolerant check Acala 1517-08 and the sensitive check glandless Acala 1517-18 GLS for screening cotton for Sandea tolerance. As compared to the tolerant check, no Upland genotype was more tolerant to Sandea, but many of them were as tolerant. However, three glandless cotton lines were the most sensitive to Sandea, which were significantly more sensitive to Sandea than all the glanded cotton tested except for PHY 499 WRF which was equally sensitive. Furthermore, seedlings at the first true-leaf stage (14 DAP) were not sensitive to Sandea, as no apparent crop injury was observed at 6 DAT. This is the first report on genotypic variation for Sandea tolerance in cotton, and the results provide useful information in cotton breeding for cultivar selection for tolerance to Sandea herbicide.