LAUSR

Abstract Waterlogging stress is a serious problem in many cotton production areas where seasonal heavy rain, floods, inappropriate irrigation or poor soil drainage are frequently encountered. In this study, 104 entries from 81 cotton genotypes including 8 Pima (Gossypium barbadense L.) and 73 Upland (G. hirsutum L.) genotypes were divided into four replicated tests under the same field conditions in 2016. The evaluation of waterlogging tolerance based on leaf color ratings was performed at the flowering stage (64 days after planting, DAP) by furrow irrigation with standing water in the field for 48 h. At 7 days after irrigation (DAI), the Pima cotton did not display any leaf color changes, indicating a high level of short-term waterlogging tolerance. A great variation in waterlogging tolerance was detected in both commercial transgenic cultivars and non-transgenic advanced breeding lines in Upland cotton, and the broad-sense heritability estimates for waterlogging tolerance ranged from 0.536 to 0.816, with an average of 0.676. When 18 lines were tested in 2–3 tests (or twice in the same test), overall consistent results in waterlogging tolerance were obtained in that seven New Mexico lines including Acala 1517-08, NM 13G2019, NM 13G1029, and NM 13R1015 and three glandless lines (Acala 1517-18 GLS, NuMex COT 15 GLS, and NuMex COT 17 GLS) and four commercial cultivars (FM 1911 GLT, FM 2322 GL, FM 2484 B2F and PHY 725 RF) were waterlogging tolerant. However, at 21 DAI, no significant differences in chlorophyll content were detected in all the three Upland cotton tests each with 32 genotypes. This study provides useful information in cotton breeding for cultivar selection for tolerance to waterlogging stress.