【摘要】 研究了无芒隐子草 (Cleistogenessongorica)和条叶车前 (Plantago lessingii)种子萌发对不同温度和水分渗透势的响应。温度在 10℃恒温至 5 0 /2 0℃变温范围内设 11个处理 ,水分渗透势在 0～ - 1.8MPa区间以 0 .2 MPa为间隔设 10个处理。结果显示 :无芒隐子草鞘内小穗的种子具有很高的生活力 ,其萌发温度幅较宽 ,在 10～ 5 0 /2 0℃温度区间 ,较高温度促进萌发 ;条叶车前种子萌发温度幅较窄 ,在 10～ 30℃温度区间 ,较低温度促进其萌发。无芒隐子草和条叶车前种子的最佳萌发温度分别为35 /2 0℃变温和 2 0℃恒温 ,在此条件下的发芽率分别达 94 %和 6 1% ,后者发芽率低的原因是种子存在生理休眠。两种植物种子萌发的最低水分阈值为 - 1.6 MPa,发芽率皆随渗透势降低而呈直线下降趋势 ,但条叶车前较无芒隐子草下降缓慢。发芽率 (y)与渗透势 (x)的回归方程 ,无芒隐子草为 y1 =- 10 .976 x1 +98.4 (r2 =0 .95 4 ) ,条叶车前为 y2 =- 5 .90 9x2 +6 0 .2 (r2 =0 .96 4 )。随着水分胁迫的加剧 ,供试种胚芽长呈逐渐下降趋势 ,但胚根长呈先增加 (无芒隐子草在 - 0 .6 MPa,而条叶车前在 - 0 .4 MPa)而后下降的趋势。讨论了两种植物种子萌发对不同温度和水分响应的生态学意义更多还原

【Abstract】 Cleistogenes songorica and Plantago lessingii are important native plant species in the north-west desert grassland of China, and play a significant role in pasture production and vegetation restoration. Research on factors affecting germination of these species has not been reported previously. A series of laboratory tests were therefore conducted to study germination response of the two species to temperature and osmotic potential. The temperature regime for both species included 5 constant temperatures（10, 15, 20, 25, 30 ℃） and 3 alternating temperature regimes（25/10, 25/15, 30/20℃）. Additional regimes were also used: 35/20, 40/20 and 50/20℃ for C. songorica, and 20/10℃ for P. lessingii. Ten osmotic potentials ranging from 0 to -1.8MPa were implemented by moistening germination paper with PEG （6000） solutions. Results showed that almost all seeds enclosed in the leaf sheath of C. songorica were viable. The germination temperature range of C. songorica was very wide and ranged from 10℃ to 50/20℃, and higher temperature promoted germination. On the other hand, P. lessingii seed had a narrow range of germination temperatures, from 10℃ to 30℃, and lower temperature promoted germination. The optimal germination temperature was 35/20℃ for C. songorica and 20℃ for P. lessingii, at which germination percentages were 94% and 61%, respectively. The reason for the low germination of P. lessingii is that some of the seeds were in dormancy. Germination declined as osmotic potential decreased from 0 to -1.6MPa, and the declining tendency in C. songorica was faster than that in P. lessingii. Regression analysis indicated that germination percentages （y） of both species were highly related to osmotic potential （x）, which can be expressed by: y₁=-10.976x₁+98.4 （r²=0.954） for C. songorica, and y₂=-5.909x₂+60.2（r²=0.964） for P. lessingii. Plumule growth was inhibited as the osmotic potential decreased; however radical growth was promoted as osmotic potential changed from 0MPa to -0.6MPa in C. songorica, and to -0.4MPa in P. lessingii, and thereafter decreased. The ecological significance of the germination response to different temperatures and osmotic potentials is discussed.更多还原