盐生植物盐穗木种子和幼苗对干旱胁迫的响应

摘 要：以盐生植物盐穗木的种子和幼苗为材料，研究干旱胁迫下盐穗木种子的萌发特性和幼苗的生理变化，以确定其对干旱胁迫的适应能力。利用PEG人工模拟干旱胁迫，检测盐穗木种子萌发期和幼苗期生长指标和生理指标的变化。结果表明：高渗透势(-0.6~-0.4 MPa)对盐穗木种子萌发有促进作用，提高其初始萌发率，并缩短其达到最终萌发率的时间，且高渗透势处理的最终萌发率与CK无显著差异，而中、低渗透势(-2.0~-0.8 MPa)对盐穗木种子萌发则有抑制作用，降低其初始萌发率，并延长其达到最终萌发率的时间；中、高渗透势(-0.7~-0.3 MPa)刺激了盐穗木幼苗做出积极的生理反应，表现为相对电导率下降、可溶性糖含量增加、过氧化氢酶(CAT)和过氧化物酶(POD)活性增强；综合种子萌发期和幼苗期的表现，盐穗木对在中、轻度干旱环境（渗透势为-0.7~-0.3 MPa）有较好的适应。

Seed and Seedling of Halostachys caspica: Response to Drought Stress

Halostachys caspica was used as material, seed germination characteristics and seedling physiological change under drought stress were studied to confirm its adaptive capacity to drought stress. PEG was used to simulate drought stress, and the growth and physiological indexes during germination and seedling stage were detected. The results showed that high osmotic potential (-0.6 to -0.4 MPa) had stimulating effect on seed germination, promoted the initial germination rate and shortened the time to the final germination rate, and the final germination rate under high osmotic potential treatment was not significantly different from that of CK. The medium and low osmotic potential (- 2.0 to - 0.8 MPa) inhibited seed germination significantly, reduced the initial germination rate and prolonged the time to final germination rate. Seedlings of Halostachys caspica were stimulated and had positive physiological responses to medium and high osmotic potential (-0.7 to -0.3 MPa). Compared with CK, relative conductivity decreased while soluble sugar content, CAT activity, and POD activity showed an increasing trend. Based on the characteristics of seed germination and physiological changes of seedlings under PEG treatments, it is concluded that Halostachys caspica can germinate and grow well at -0.7 to -0.3 MPa osmotic potential.