乌苏里鼠李种子休眠机理及萌发特性研究

Seed dormancy mechanism and germination characteristics of Rhamnus ussuriensis

【目的】确定乌苏里鼠李种子休眠类型,探索有效解除种子休眠的方法,为其种质资源利用、种子扩繁等提供理论指导。【方法】以2018年9月采集的乌苏里鼠李种子为材料,研究种子的生物学特性、吸水特性、休眠特性以及种子内源抑制物活性,确定种子的休眠类型;用体积分数98%H2SO4、质量分数5.5%NaClO、热水和不同浓度(1,2,3 mol/L)NaOH对乌苏里鼠李种子进行处理,探索解除种子休眠的有效方法。【结果】乌苏里鼠李种子成熟后,种皮为黄褐色至黑褐色,种皮有蜡质,种子长形卵圆状,表皮光亮、质地坚实、结构致密、种胚紧密;千粒质量为(19.6±1.0)g;纵径为(5.0±0.2)mm,横径为(3.8±0.2)mm。在室温条件下,乌苏里鼠李种子的吸水率随浸种时间的增加呈抛物线型变化,表明其种皮透水性良好,对种子的吸水阻碍较小。乌苏里鼠李种子的生活力平均值为96%,但发芽率和发芽势均为0%,种子本身具有休眠特性。随着乌苏里鼠李种子浸提液质量浓度的增加,内源抑制物对白菜种子发芽率和根长的抑制作用均明显增加,对白菜种子根长的抑制活性呈上升趋势。采用体积分数98%H2SO4和质量分数5.5%NaClO处理乌苏里鼠李种子,均不能解除其种子休眠;分别采用40~60℃热水浸种20 min或者1~3 mol/L NaOH浸种20~120 min,均具有破解其种子休眠的作用。【结论】种皮障碍和内源抑制物是限制乌苏里鼠李种子发芽的主要原因,乌苏里鼠李种子属于综合休眠型;40℃热水处理20 min或1 mol/L NaOH处理40 min可有效解除种子休眠。

【Objective】The seed dormancy type of Rhamnus ussuriensis and the effective methods for releasing seed dormancy were explored to provide guidance for utilization of germplasm resources and seed propagation.【Method】The biological characteristics,water absorption characteristics,dormancy characteristics and activity of endogenous inhibitors of Rhamnus ussuriensis seeds collected in September 2018 were investigated to determine the dormancy type.The effects of 98%sulfuric acid(H2SO4),5.5%sodium hypochlorite(NaClO),hot water and sodium hydroxide(NaOH)at different concentrations(1,2 and 3 mol/L)on seeds were studied to explore an effective way to release dormancy.【Result】The testa of mature Rhamnus ussuriensis seeds was waxy and yellow brown to black brown in color.The seeds were long and oval with bright epidermis,solid texture,dense structure,and tight embryo.The mass of 1000 grains was(19.6±1.0)g,the longitudinal diameter was(5.0±0.2)mm,and the transverse diameter was(3.8±0.2)mm.At room temperature,the water absorption of Rhamnus ussuriensis seeds changed in parabola shape with the increase of soaking time,which indicated that its testa had good water permeability and little water absorption obstruction to seeds.The average viability of Rhamnus ussuriensis seeds were 96%,and the average germination rate and germination potential were 0%.It can be seen that seeds had dormancy characteristics.With the increase of concentration of NaOH,the inhibition of endogenous inhibitors on germination rate and root length of Brassica pekinensis seeds increased significantly,and the inhibition activity on the root length of B.pekinensis seed increased as well.The seeds of Rhamnus ussuriensis treated with 98%H2SO4 by volume and 5.5%NaClO by mass could not be released from dormancy.The dormancy was released when seeds were soaked in hot water at 40-60℃for 20 minutes or 1-3 mol/L NaOH for 20-120 minutes,respectively.【Conclusion】Seed coat obstacle and endogenous inhibitor were the main factors restricting germination of Rhamnus ussuriensis seeds.The Rhamnus ussuriensis seeds belonged to the comprehensive dormancy type.The seed dormancy could be released effectively by 40℃hot water treatment for 20 min or 1 mol/L NaOH treatment for 40 min.