盐胁迫对裸果木幼苗生长和叶片抗逆生理指标的影响

Response of Seedling Growth and Leaf Resistance Physiological Indexes of Gymnocarpos przewalskii to NaCl Stress

裸果木起源于古地中海,为亚洲中部荒漠区分布的第三纪孑遗植物种,对研究旱生植物演化过程具有重要的科学价值。以一年生裸果木(Gymnocarpos przewalskii)实生苗为材料,在盆栽条件下用质量浓度为0.4%、0.8%、1.2%和1.6%的NaCl溶液进行盐胁迫处理,测定各NaCl处理下裸果木幼苗叶片的抗氧化酶活性、渗透调节物质含量、叶绿素含量、相对电导率(REC)、丙二醛(MDA)含量以及株高、基径,根、茎、叶、总干重,根冠比变化,探讨裸果木幼苗对盐胁迫的生理耐受性。结果显示,(1)随着盐胁迫程度的加重,裸果木幼苗株高、基径,以及根、茎、叶干重和总干重整体呈下降趋势,而根冠比呈上升趋势;裸果木幼苗株高、基径和根干重在0.4%NaCl处理下较对照变化不显著,但其茎干重、叶干重和总干重在各NaCl处理下均显著低于对照。(2)随着盐胁迫程度的加重,裸果木幼苗叶片的可溶性糖(SS)含量、可溶性蛋白(SP)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性均先升高后降低,而脯氨酸(Pro)含量、过氧化氢酶(CAT)活性、REC、MDA含量均呈持续升高趋势;在0.8%NaCl处理下,叶片SS、SP含量下降,SOD、POD活性减弱,REC、MDA含量显著升高,严重抑制了干物质的合成与积累。(3)随着盐胁迫程度的加重,裸果木幼苗叶片的叶绿素a含量、叶绿素b含量、总叶绿素含量和类胡萝卜素含量均明显降低。研究发现,在盐胁迫条件下,裸果木幼苗的生长受到了不同程度的抑制,其叶片可以通过提高渗透调节物质含量和增强抗氧化酶系统活性来适应盐胁迫环境,从而具备一定的耐盐能力;当NaCl浓度超过0.4%时,裸果木生长显著受抑,渗透调节和抗氧化能力有所减弱,膜系统受到明显的损伤。

Gymnocarpos przewalskii is a tertiary relict plant species distributed in the desert area of central Asia,which originated from the ancient Mediterranean Sea.Using one-year-old Gymnocarpos przewalskii seedlings as materials,we treated the leaves of G.przewalskii seedlings with 0.4%,0.8%,1.2%and 1.6%NaCl solution under potted conditions,and measured the activities of antioxidant enzymes and contents of osmotic regulatory substances,Chlorophyll content,relative electrical conductivity(REC),malondialdehyde(MDA)content,plant height,base diameter,root,stem,leaf,total dry weight,root-shoot ratio under NaCl treatment,to investigate the physiological tolerance to salt stress of G.przewalskii seedlings.The results showed as follows,(1)with the increase of salt stress,plant height,base diameter,root dry weight,stem dry weight,leaf dry weight and total dry weight showed a decreasing trend,while the root-shoot ratio showed an increasing trend.The seedling height,base diameter and root dry weight did not change significantly under 0.4%NaCl treatment,but the stem dry weight,leaf dry weight and total dry weight were significantly lower than the control under each NaCl treatment.(2)With the aggravation of salt stress,the contents of soluble sugar(SS),soluble protein(SP),activities of superoxide dismutase(SOD)and peroxidase(POD)in leaves of G.przewalskii seedlings firstly increased and then decreased,while proline(Pro)content,catalase(CAT)activity,REC and MDA contents all showed an increasing trend.Under 0.8%NaCl treatment,SS and SP contents decreased,SOD and POD activities weakened,REC and MDA contents increased significantly,which severely inhibited the synthesis and accumulation of dry matter.(3)With the aggravation of salt stress,the contents of chlorophyll a,chlorophyll b,chlorophyll a+b and carotenoid in the leaves of G.przewalskii seedlings decreased significantly.The comprehensive analysis showed that the growth of G.przewalskii seedlings was inhibited to different degrees under salt stress.The leaves of G.przewalskii could adapt to the salt stress environment by regulating osmotic regulatory substances and antioxidant enzymes system,and thus had a certain ability of salt tolerance.When NaCl concentration exceeds 0.4%,the growth was significantly inhibited,osmotic regulation and antioxidant capacity were weakened,and the membrane system was obviously damaged.