间歇淹水和氨氮胁迫对3种园林植物形态与生理的影响特征

Effects of Intermittent Flooding and Ammonia Nitrogen Stress on Morphology and Physiology of Excoecaria cochinchinensis,Nerium oleander,Fagraea ceilanica

为加深对红背桂(Excoecaria cochinchinensis)、夹竹桃(Nerium oleander)、灰莉(Fagraea ceilanica)3种园林植物在间歇性淹水和高浓度氨氮环境下耐受性的了解,设置6种氨氮浓度(0、0.5、7.5、14.5、21.5、28.5 mg/L)水溶液的间歇淹水栽培试验,连续试验90 d,测定红背桂、夹竹桃、灰莉的形态和生理指标,以期为3种植物在雨水花园、潜流湿地、间歇淹水绿地等环境中的应用提供理论参考。结果表明:(1)与土培对照相比,间歇淹水下,3种植物均出现茎基皮孔肥大和根部不定根生成等强化向根系输送氧气的适应性变化,且显著促进夹竹桃株高生长,而红背桂和灰莉受到淹水的影响生长速率减慢;(2)间歇淹水与氨氮互作下,夹竹桃株高随氨氮浓度增大而增加,而红背桂和灰莉在氨氮达14.5 mg/L后,株高生长显著受抑,当氨氮达21.5 mg/L时,前者叶片出现失绿等受害症状;(3)间歇淹水对3种植物抗氧化酶活性以及叶绿素、丙二醛(MDA)、游离脯氨酸(Pro)、可溶性蛋白(SP)等含量影响不显著,在前60 d时3种植物抗氧化酶活性、游离脯氨酸、可溶性蛋白含量均出现一定波动,但90 d时各项指标与土培相比差异不大;(4)间歇淹水与氨氮互作下,在90 d时,夹竹桃即使在氨氮达28.5 mg/L时,各项指标依然能够恢复到正常水平,红背桂和灰莉在氨氮达14.5 mg/L后,均倾向于产生更多的抗氧化酶、MDA和Pro,且SP下降,生理失调特征明显。由此可见,夹竹桃在0~28.5 mg/L的氨氮浓度水溶液中均表现出积极的形态适应及较强的抗性,能在一定的时长及间歇淹水环境下生长。红背桂、灰莉虽然也表现出较强的适应性,但对于氨氮的耐受性弱于夹竹桃,仅在0~14.5 mg/L的氨氮浓度水溶液范围内生长良好。因此,3种植物均可应用于间歇淹水绿地中,夹竹桃对高浓度氨氮水环境有较强适应性。

In order to deepen the understanding of the tolerance of Excoecaria cochinchinensis,Nerium oleander and Fagraea ceilanica to intermittent flooding and high concentration of ammonia nitrogen,an intermittent flooding cultivation experiment was conducted with six aqueous solutions of ammonia nitrogen concentration(0,0.5,7.5,14.5,21.5,28.5 mg/L).After 90 days of continuous test,the morphological and physiological indexes of the three plants were determined,aimed to provide theoretical references for the application of the three plants in rain garden,subsurface flow wetland,intermittent flooded green space and other environments.The results showed that:(1) Compared with the soil culture control,under intermittent flooding,all three plants showed adaptive changes in enhancing oxygen delivery to the roots,such as enlarged stem base lenticels and adventitious root formation,and significantly promoted the height growth of N.oleander.However,the growth rate of E.cochinchinensis and F.ceilanica was slowed down due to the influence of flooding;(2) Under the interaction of intermittent flooding and ammonia nitrogen,the plant height of N.oleander increased with the increase of ammonia nitrogen concentration,while the plant height growth of E.cochinchinensis and F.ceilanica was significantly inhibited after the ammonia nitrogen reaching 14.5 mg/L,and when the ammonia nitrogen was 21.5 mg/L,the leaves of E.cochinchinensis appeared symptoms such as reduced leaf area and green loss;(3) Intermittent flooding had no significant effect on the activities of antioxidant enzymes and the contents of chlorophyll,malondialdehyde(MDA),free proline(Pro) and soluble protein(SP) of the three plants.On the 60th days,the activities of antioxidant enzymes,free proline and soluble protein of the three plants fluctuated to some extent,but on the 90th day,each index had little difference compared with soil culture;(4) Under the interaction of intermittent flooding and ammonia nitrogen,on the 90th day,N.oleander could recover to the normal level even when the ammonia nitrogen was 28.5 mg/L.After the ammonia nitrogen was 14.5 mg/L,E.cochinchinensis and F.ceilanica tended to produce more antioxidant enzymes,MDA and free proline,less soluble protein,with obvious physiological disorders.It could be seen that N.oleander showed active morphological adaptation and strong resistance in the aqueous solution with ammonia nitrogen concentration of 0-28.5 mg/L,and could grow in a certain length of time and intermittent flooding environment.Although E.cochinchinensis and F.ceilanica also showed strong adaptability,the tolerance to ammonia nitrogen was weaker than that of N.oleander,and they only grew well in the range of 0-14.5 mg/L ammonia nitrogen concentration aqueous solution.Therefore,the three plants could be used in the intermittent flooded green space,and N.oleander has strong adaptability to high concentration ammonia nitrogen water environment.