硅提高黄瓜幼苗抗盐能力的生理机制研究

Studies on Physiological Mechanism of Salt Resistance Improved by Silicon in Cucumber

为了明确硅提高黄瓜幼苗抗盐能力的机制,该试验采用水培方法,以黄瓜品种‘津优一号’为材料,对幼苗进行中度盐胁迫,研究在盐胁迫下硅对黄瓜幼苗生长、光合特性、渗透调节物质和离子吸收的影响。结果显示:(1)正常条件下,硅对黄瓜幼苗生长及相关生理指标无明显影响;单独盐处理降低了幼苗叶片叶绿素含量、光合速率、气孔导度、蒸腾速率和叶片含水量,导致幼苗生长受抑。(2)盐胁迫下加硅显著提高了幼苗光合速率和叶片含水量,增加了生物量的积累;在盐胁迫初期,硅加盐处理黄瓜叶片渗透势略低于单独盐处理,此后均高于单独盐处理;硅加盐处理显著提高了叶片可溶性糖含量,尤其是蔗糖含量,而降低了其脯氨酸含量,但对可溶性蛋白含量无显著影响。(3)盐胁迫下黄瓜植株Na+含量大幅上升,K+含量下降,K+/Na+比大幅降低;硅加盐处理降低了黄瓜叶片中Na+含量,提高了K+含量和K+/Na+比。研究表明,盐胁迫条件下,硅能通过减轻叶片离子毒害和增加水分吸收,改善叶片水分状况,从而维持较高的光合能力,提高其抗盐能力;而渗透调节只在盐胁迫初期有轻微缓解作用,不是硅提高黄瓜幼苗抗盐性的主要途径。

In order to clarify the mechanism of silicon enhancing plant salt resistance,Cucumis sativus L.cv ‘Jinyou No.1’ was grown in the hydroponic solution with silicon and NaCl.The effects of silicon on growth,photosyntheisis,osmotic adjustment and ion accumulation in cucumber seedlings were investigated.（1）Application of silicon alone had no effects on cucumber growth,while it partly reversed the salt-induced reduction in plant growth,chlorophyll content,water content,photosynthesis,stomatal conductance and transpiration.（2）The osmotic potential of silicon application was lower at beginning of salt stress,then became higher than salt alone application.Meanwhile,the osmolytes,especially,the sucrose levels,but not the proline,were significantly increased than that without silicon application under salt stress.The soluble protein content was not affected by silicon application.（3）Na＋ concentration was increased while K＋ concentration and K＋/Na＋ ratio were decreased in salt-treated plants.While,this tendency was partly reversed by silicon application,especially in the leaves.It can be concluded that silicon application decreases Na＋ toxicity and improves the water status in plant,which allows a higher photosynthesis and growth rate,lead to salt tolerance.Osmotic adjustment,which has little effect at the beginning of salt stress,is not the main factor of silicon improving the salt tolerance.