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Investigating seed dormancy in cotton ( Gossypium hirsutum L.): understanding the physiological changes in embryo during after‐ripening and germination
Author(s) -
Wang L. R.,
Yang X. N.,
Gao Y. S.,
Zhang X. Y.,
Hu W.,
Zhou Z.,
Meng Y. L.
Publication year - 2019
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/plb.13005
Subject(s) - germination , biology , dormancy , abscisic acid , ripening , seed dormancy , gibberellic acid , horticulture , embryo , imbibition , botany , biochemistry , gene , microbiology and biotechnology
Abstract The dormancy of seeds of upland cotton can be broken during dry after‐ripening, but the mechanism of its dormancy release remains unclear. Freshly harvested cotton seeds were subjected to after‐ripening for 180 days. Cotton seeds from different days of after‐ripening (DAR) were sampled for dynamic physiological determination and germination tests. The intact seeds and isolated embryos were germinated to assess effects of the seed coat on embryo germination. Content of H 2 O 2 and phytohormones and activities of antioxidant enzymes and glucose‐6‐phosphate dehydrogenase were measured during after‐ripening and germination. Germination of intact seeds increased from 7% upon harvest to 96% at 30 DAR, while embryo germination improved from an initial rate of 82% to 100% after 14 DAR. Based on T 50 (time when 50% of seeds germinate) and germination index, the intact seed and isolated embryo needed 30 and 21 DAR, respectively, to acquire relatively stable germination. The content of H 2 O 2 increased during after‐ripening and continued to increase within the first few hours of imbibition, along with a decrease in abscisic acid (ABA) content. A noticeable increase was observed in gibberellic acid content during germination when ABA content decreased to a lower level. Coat removal treatment accelerated embryo absorption of water, which further improved the accumulation of H 2 O 2 and changed peroxidase content during germination. For cotton seed, the alleviation of coat‐imposed dormancy required 30 days of after‐ripening, accompanied by rapid dormancy release (within 21 DAR) in naked embryos. H 2 O 2 acted as a core link between the response to environmental changes and induction of other physiological changes for breaking seed dormancy.