Purpose This paper aimed to investigate the regulatory effects of temperature on the release of seed dormancy in Paris polyphylla, attempting to elucidate the temperature-responsive mechanism of morphological after-ripening and provide a theoretical foundation for establishing an efficient, large-scale seedling propagation system.
Methods The germination behaviors and histological embryo development of seeds were systematically evaluated under different stratification temperatures (4, 15, 18, 21, 24, 27, and 30 ℃). Concurrently, the dynamic profiles of antioxidant enzyme activities and endogenous hormones were determined.
Results The optimal temperature for both seed germination and morphological after-ripening was identified as 21 ℃, at which germination initiated after 45 d of stratification and reached 86.4% by day 75. Embryo after-ripening exhibited a highly sensitive and narrow temperature adaptability, deviations from 21 ℃ severely hindered the development of embryos, manifested as a significant deceleration at lower temperatures (4 and 15 ℃) and a complete developmental arrest from the globular to the cotyledonary stage at high temperatures (27 and 30 ℃). During the dormancy release process, the activities of key antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the contents of endogenous hormones (gibberellin, abscisic acid, indole-3-acetic acid, and cytokinin) displayed regular fluctuations in response to the developmental stages of the embryo.
Conclusion Seeds of P. polyphylla possess profound morphological dormancy governed by a strict and narrow temperature-dependent regulation of embryo after-ripening. Stratification at 21 ℃ represents the indispensable ecological thermal window for dormancy alleviation, whereas the complete developmental block triggered by higher temperatures aligns with the biological hallmarks of thermodormancy, serving as a critical adaptive trait for surviving seasonal temperature transitions in its natural habitat.
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