苦豆子和披针叶黄华种子萌发和幼苗生长对干旱胁迫的响应

以采集于河西走廊中部荒漠边缘的苦豆子(Sophora alopecuroides L.)和披针叶黄华(Thermopsis lanceolate L.)种子为试验材料, 以不同渗透势PEG-6000 溶液模拟干旱条件, 研究了2 种植物种子萌发和幼苗生长对干旱胁迫的响应特征。研究结果显示, 随着干旱胁迫程度的加剧, 2 种植物种子吸胀速率、萌发率、萌发指数、活力指数、苗高、根长和组织饱和含水量等指标均表现出明显降低趋势, 而幼苗干重、根干重和根冠比均呈先升后降趋势。2 种植物种子萌发对干旱胁迫均较为敏感, 苦豆子和披针叶黄华种子能够萌发的最低渗透势阈值分别为-0.65 MPa 和-0.42 MPa。2 种植物因干旱胁迫未能萌发的种子复水后萌发率均较高。分析认为, 2 种植物种子萌发和幼苗生长对干旱胁迫的响应特征对幼苗的成功定植和种群的自然更新具有重要生态学意义, 但在人工栽培时保证土壤墒情应是保障建植成功的关键措施。

Response of Sophora alopecuroides and Thermopsis lanceolata seed germination and growth to drought stress

Seed germination and seedling stages are not only crucial stages of the life span of plants, but also important adaptation stages to different environmental conditions. The response of Sophora alopecuroides L. and Thermopsis lanceolate L. seed germination and seedling growth to drought stress in border desert lands of the Hexi Corridor were investigated under simulated drought conditions of polyethylene glycol-6000 (PEG) with -0.03 MPa, -0.10 MPa, -0.24 MPa, -0.42 MPa, -0.65 MPa and -0.94 MPa osmotic potentials. The main objectives of the study were to reveal the adaptive mechanisms of desert plants and to provide further technical guidance on seedling cultivation and restoration of desert vegetation. The result showed that the rate of seed water uptake, germination percentage, germination index, vigor index, seedling height, root length and plant water content decreased with increasing PEG drought stress. However, seedling and root dry weight and root/shoot ratio initially increased followed by a decrease. Furthermore, seed germination was sensitive to drought stress. The lowest osmotic potential threshold was -0.65 MPa for S. alopecuroides seeds and -0.42 MPa for T. lanceolate seeds. For seeds incapable of germination under drought stress, germination percentage was high once water was recovered. The results suggested that response of seed germination and seedling growth to drought stress was ecologically essential for later establishment of seedlings and vegetation. In artificial cultivation, however, a key step for successful planting was guaranteed soil moisture.