低温胁迫对蔓性千斤拔种子萌发及生理指标的影响

目的]探讨蔓性千斤拔种子对逆境的适应性,为适时生产播种提供参考依据.方法]将适温培养2d的种子置于6℃条件下胁迫12、48、72 h和在6℃冷吸胀后适温培养,测定其发芽率、发芽指数、平均发芽速度及可溶性糖、蛋白质、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性等生理指标.结果]经低温胁迫和冷吸胀处理后,蔓性千斤拔种子发芽均受到不同程度的影响,其中低温胁迫72 h和冷吸胀处理的发芽率及低温胁迫48、72 h和冷吸胀处理的发芽指数和发芽速度显著低于对照;不同处理种子可溶性糖、脯氨酸( Pro)、可溶性蛋白含量均高于对照,部分处理达显著水平.在种子萌发过程中,对照处理的种子POD活性不断降低,而低温胁迫48、72 h处理的种子POD活性先上升、后保持在一定水平上,低温胁迫12h处理的种子POD活性呈先上升后下降的趋势.低温胁迫48、72 h处理的萌发种子SOD活性呈先升高后下降的趋势,而对照、低温胁迫12h处理及冷吸胀处理则呈逐渐降低的趋势.结论]在一定时间的低温胁迫下,虽然蔓性千斤拔种子萌发受到不同程度的影响,但是膜保护酶系统及渗透调节能主动响应;而冷吸胀处理的蔓性千斤拔种子,不仅萌发受到严重影响,而且膜保护酶系统受到不可逆转的破坏.

Effect of low temperature stress on seed germination and physiological characteristics of Flemingia philippinensis

Object]The present experiment was conducted to explore the adaptability of Flemingia philippinensis seeds under adverse environmental conditions,especially the low temperature for selecting suitable seeding period.Method]The Flemingia philippinensis seeds were cultured at appropriate temperature for 15 days after treatment of cold imbibition and low temperature(6℃) stress for 12,48,72 h(after 2 days culture at optimum temperature).The germination indices and physiological parameters such as soluble sugar and protein content,and activities of superoxide dismutase(SOD) and peroxidase(POD) were determined during seed germination.Result]The germination rate of seeds stressed for 72 h at low temperature and cold imbibition,and the germination index and average germination rate of seeds stressed for 48 and 72 h at low temperature and cold imbibition were significantly lower than that of control.The soluble sugar,proline and soluble protein content in seeds increased under different low temperature stress compared to control.During seed germination,the POD activity in seeds did not showed any specific trend.In low temperature treatment of 12 h,it initially increased and then decreased,while in 48 and 72 h low temperature treatments it showed an increasing trend initially and then remained constant.The SOD activity in seeds treated with 48 and 72 h low temperatures also not showed any specific trend,however,it was lesser in control and seeds treated with 12 h low temperature.Conclusion]It may be concluded that the antioxidative defense system and osmosis adjustment in germinating seeds varied in response to low temperature stress within a certain period.However,cold imbibition stress not only seriously affected the germination of seeds,but also resulted in severe and irreversible damages in protective enzyme defense system of membrane.