低温条件下γ-氨基丁酸对扁蓿豆种子萌发的影响

Effects of γ-aminobutyric acid on seed germination of Medicago ruthenica under low temperature

摘要:

【目的】提高低温下种子萌发期和早期幼苗生长期扁蓿豆耐寒性。【方法】模拟高寒草甸 5 月地温，研究不同 GABA 浓度下扁蓿豆种子萌发情况以及最佳浓度下 GABA 对其种子淀粉酶活性、根系活力和种子表型特性的影响 。【结果】低浓度（0. 1~1. 0 mmol/L）的 GABA 可促进种子萌发 。 0. 5 mmol/L 的浸种处理为最佳效应浓度，此浓度下种子发芽势、发芽指数、活力指数、正常种苗数、胚根胚芽长和苗干重显著提高 48. 03%、28. 36%、44. 54%、7. 41%、27. 33%、21. 23% 和 10. 17%，同时显著缩短平均发芽时间 4. 72%。通过 0. 5 mmol/L 的 GABA 浸种浓度对常温和低温处理下 α-淀粉酶活性、根系活力和种子表型特征的探究，得出常温（25 ℃）下，GABA 对 α-淀粉酶活性和根系活力有提高作用， 但未达到显著水平，对种子表型几乎无影响，但此浓度可显著增强低温下萌发前期（萌发 4 d）种子中的 α-淀粉酶活性，提高种子根系活力，缓解低温下幼苗发育不良和生长较慢的情况，促进幼苗生长发育。 【结论】0. 5 mmol/L 的 GABA 浸种处理是提高低温下扁蓿豆耐寒性的最佳浓度。

Abstract:

【Objective】 To improve the cold tolerance of Medicago ruthenica during seed germination and seed- ling growth period under low temperature.【Method】 We studied the germination of M. ruthenica seeds under differ- ent GABA concentrations. We explored the effects of GABA on seed α-amylase activity，root activity and seed pheno- typic characteristics at the optimal concentration by simulating the ground temperature of alpine meadow in May. 【Result】 Low concentration of GABA （0. 1~1 mmol/L） could promote seed germination，with a concentration of 0. 5 mmol/L GABA being the optimal concentration. At this concentration，the germination potential，germination in- dex，vigor index，number of normal seedlings，radicle and germ length and seedling dry weight were significantly in- creased by 48. 03%，28. 36%，44. 54%，7. 41%，27. 33%，21. 23% and 10. 17%，respectively，and the average ger- mination time was significantly shortened by 4. 72%. Moreover，under normal temperature treatment （25 ℃） GABA （0. 5 mmol/L） could improve α-amylase activity and root activity，but did not reach the significant level，and had little effect on seed phenotype. Different from normal temperature，GABA significantly enhanced the α-amylase activity of M. ruthenicaat at the early germination stage （germination 4 d） under low temperature. It also improved the root activity，alleviated the slow growth of seedlings and slim seedlings，and promoted the growth and development of M. ruthenica.【Conclusion】 The optimum GABA concentration to improve the cold tolerance of M. ruthenica is 0. 5 mmol/L under low temperature.