3种园林植物的抗盐光合特性

研究狗牙花、红背桂和花叶假连翘叶片的光合作用对盐胁迫的响应,揭示3种幼苗耐盐胁迫的能力,以便为滨海盐土的园林植物选择提供参考。通过利用人工浇盐的方式模拟野外盐环境,测定植物光合指标,并用主成分方法评定各种园林植株的抗盐性。结果表明,随着盐胁迫时间的延长,在0.3%盐浓度胁迫下,3种幼苗的Pn不断下降;狗牙花与花叶假连翘的Gs和Ci不断下降,红背桂先升后降;狗牙花与红背桂的Tr不断下降,花叶假连翘先降后升。在0.6%盐浓度胁迫下,3种幼苗的Pn持续下降;狗牙花的Gs先降后升,红背桂与花叶假连翘下降。狗牙花、花叶假连翘的Ci先降后升,红背桂持续下降;3种幼苗的Tr先降后升。采用主成分分析法对3种植株的光合指标进行综合评价,显示盐浓度胁迫下的3种植物幼苗的光合指标得分为红背桂狗牙花花叶假连翘。3种苗木中,红背桂叶片能维持较高的光合活性,更适于盐碱地栽培,而花叶假连翘的耐盐胁迫能力弱。

Photosynthetic characteristics of three garden plants in response to salt stress

In order to provide a reference for the selection of garden plants in saline land, leaf photosynthetic responses of Ervatamia divaricata, Excoecaria cochinchinensis and Duranta repens to salt stress were studied, and their differences in leaf photosynthetic characters under salt stress were compared. The experimental seedlings were placed in a simulated salt environment, and their photosynthetic indexes were determined, and the principal component method was used to evaluate their salt resistance. The results showed that at 0.3 % salt concentration, with increasing salt stress time, P_n of the three species continuously decreased; G_s and C_i of E. divaricata and D. repens continuously decreased, whereas E. cochinchinensis increased and then decreased; T_r of E. divaricata and E. cochinchinensis continuously decreased, whereas D. repens decreased followed by an increase. At 0.6 % salt concentration, P_n of the three species continuously decreased, G_s of E. divaricata decreased followed by an increase, while the other two species decreased; C_i of E. divaricata and D. repens decreased followed by an increase, whereas E. cochinchinensis continuously decreased; T_r of the three species of seedlings decreased followed by an increase. Principal component analysis showed that under salt stress, photosynthetic index scores of the three species seedlings decreased in the order of E. cochinchinensis > E. divaricata > D. repens. Among these seedlings, E. cochinchinensis possessed the highest leaf photosynthetic activity. Therefore, E. cochinchinensis has stronger salt tolerance and is more suitable for use in salt land, whereas D. repens has weaker salt tolerance compared with the others.