关键词: 山桐子, 休眠解除, 萌发, 内源激素

Abstract: [Objective] This study investigated the relationship between the dynamic changes of endogenous hormones and seeds germination after dormancy release to provide a basis for clarifying the mechanism of seed germination of Idesia polycarpa, and to provide a theoretical basis and technical support for the breeding and application of I. polycarpa.[Method] The endogenous hormones contents of I. polycarpa seeds from Jiyuan provenance were determined by enzyme-linked immunosorbent assay.[Result] 1) Under the constant temperature of 25 ℃, the seeds germination rate of I. polycarpa was less than 10%; Under the variable temperature condition of 15 ℃/25 ℃, the germination rate of the seeds without prechilling treatment was 33%~37%; With the extension of the chilling treatment time at 5℃, the germination rate increased gradually, and the germination rate reached to 98.0% in 60 d. 2) Under the variable temperature condition of 15 ℃/25 ℃, IAA, GA₃ and ZR contents were significantly higher than that under the constant temperature of 25 ℃. However the ABA content was just the opposite, and the ratio of (IAA+GA₃+ZR)/ABA and GA₃/ABA became larger. 3) Under the variable temperature condition, IAA and ABA contents showed a decreasing trend, while GA₃ and ZR contents first increased and then decreased during the germination process of seeds without prechilling treatment. But the contents of IAA, GA₃ and ZR in seeds prechilled all increased first and then decreased except for ABA, the difference was only the time of peak appearance. 4) With the increase of prechilling time, the (IAA+GA₃+ZR)/ABA and GA₃/ABA ratios increased first, respectively reached to 3.8±0.2, 2.0±0.1, and then decreased during the germination process, but time reaching the peak was different among different periods of prechilling, the peak time of prechilling treatment for 0, 20, 40 d and 60 d was at 20, 12, 12 d and 8 d, respectively. 5) There was no consistent correlation between the seeds germination rate and the single endogenous hormone among the prechilling periods, but the germination rate was significantly correlated with ratios of (IAA+GA₃+ZR)/ABA and GA₃/ABA.[Conclusion] The seeds of Idesia polycarpa from Jiyuan provenance have obvious dormancy characteristics. Under the variable temperature condition, experiencing the chilling treatment time at 5℃, the earlier the (IAA+GA₃+ZR)/ABA and GA₃/ABA ratios in seeds reached to peak, the higher the germination rate was. When the peak time of the ratios was shortened to 8 d, the germination rate was the highest. The effect of prechilling on dormancy release is to reach the equilibrium state of endogenous hormones early in the germination process.

Key words: Idesia polycarpa, dormancy release, germination, endogenous hormone