盐胁迫下罗汉松生长和生理变化的研究

室内水培条件下设计盐胁迫梯度试验,通过新梢生长量、新根数等形态指标和Na 、K 含量比、脯氨酸含量、叶绿素含量、SOD活性等生理指标的测定,研究了罗汉松幼苗在不同盐胁迫条件下的动态响应过程.结果表明:(1)罗汉松在盐胁迫初期,低盐条件下有利新梢生长,高盐条件下抑制新梢生长;但延长胁迫时间,低盐条件也一定程度地抑制新梢生长.(2)在低盐和中盐条件下罗汉松仍能发根,但高盐条件下新根发生基本停止.(3)随着胁迫程度加剧和胁迫时间延长,Na 、K 含量比呈上升趋势,但低盐和中盐条件下Na 、K 含量比值较接近,而高盐条件下Na 、K 含量比明显升高.(4)不同程度的盐胁迫使脯氨酸含量显著增加,但随胁迫时间延长,脯氨酸含量呈下降趋势.(5)叶绿素在低盐条件下未受明显破坏,但在中盐和高盐条件下受破坏较大.(6)胁迫初期,SOD在低盐和中盐条件下活性较高,高盐条件下活性降低;胁迫后期,低盐条件下SOD活性维持较高水平,但中盐和高盐条件下SOD明显下降.

Growth and Physiological Changes of Podocarpus macrophyllus under Salt Stress

A salt stress trial is carried out under a solution culture condition.Morphological indices such as new branch growth length and new root number,and physiological indices such as the ratio Na /K ,proline concentration,chlorophyll concentration,and SOD activities,of P.macrophyllus are measured and analyzed during salt stress experiments.The results indicate that:(1) low salt stress is beneficial to new branch growth;high salt stress hinders the growth in the initial stages and low salt stress also does so when the period of salt stress is prolonged;(2) roots can still radiate under low or medium salt stress levels but the radiation is seriously hindered under high salt stress;(3) the ratio Na /K increases with the exposure time and the salt stress level;it differs only slightly between low and medium salt stress levels but is significantly higher under high salt stress;(4) proline concentration goes up substantially with increased stress but it decreases under long-term tress;(5) chlorophyll is slightly damaged under low stress and severely damaged under medium and high salt stress levels;and(6) at the beginning of stress exposure,SOD activity is high under high salt stress and low under low stress but after the initial period,SOD activity remains high under low salt stress conditions and rapidly decreases under medium and high salt stress levels.