外源ABA对楸树幼苗NaCl胁迫的缓解效应及其生长生理响应特征

以2年生楸树(苏楸1号和008-1)扦插苗为材料,采用盆栽试验法,分析盐胁迫(0.5%NaCl)处理下楸树幼苗生长、生理的变化,并分析不同浓度外源ABA(15、25、35 mg/L)对盐胁迫(30 d)楸树幼苗的缓解效应及其生理生化特性,以探索重度盐胁迫下适合楸树幼苗生长的适宜外源ABA浓度,为增强盐碱地楸树的耐盐性、提高盐碱地的利用提供理论依据。结果显示:(1)0.5%NaCl胁迫下,两品种楸树幼苗叶片表现出不同程度的盐害症状,且‘苏楸1号’叶片盐害症状较‘008-1’严重;随胁迫时间延长,两品种楸树幼苗的相对电导率(REC)均呈先上升后下降的变化趋势,叶绿素(Chl)、相对含水量(RWC)均呈降低趋势,可溶性糖(SS)、可溶性蛋白(SP)、脯氨酸(Pro)以及超氧化物歧化酶(SOD)活性均呈先上升后下降趋势,但‘008-1’的REC显著低于‘苏楸1号’,Chl、RWC、SS、SP、Pro、SOD均显著高于苏楸1号,表明‘008-1’的耐盐性较‘苏楸1号’更强。(2)喷施外源ABA使得盐胁迫下‘008-1’楸树的苗高显著增加、新叶提前萌发,表明外源ABA在一定程度上能够缓解盐胁迫对楸树生长的影响;喷施外源ABA降低了盐胁迫下‘008-1’楸树幼苗叶片的REC,提高了Chl、RWC、SS、SP、Pro、SOD、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,促进了内源激素生长素(IAA)、脱落酸(ABA)、赤霉素(GA3)以及玉米素核苷(ZR)的积累。研究表明,楸树品种‘008-1’的耐盐性更强;外源喷施适宜浓度ABA能够缓解盐胁迫对楸树幼苗生长的影响,降低幼苗叶片细胞膜透性,促进幼苗渗透调节物质的积累,增强渗透调节能力,并提高盐胁迫下幼苗的抗氧化酶活性,促进植物对内源激素含量的调节,从而提高楸树的耐盐性,且以25 mg/L ABA处理的效果最好。

Alleviating Effects of Exogenous ABA on Catalpa bungei Seedlings under NaCl Stress and Growth Physiological Response Characteristics

In this study, the cuttings of 2-year-old Catalpa bungei tree were taken as materials and pot experiment was adopted, the growth and physiological changes of C. bungei seedlings under 0.5% salt stress were studied, and the alleviating effects of different concentrations of exogenous ABA (15, 25, 35 mg/L) on C. bungei seedlings under salt stress were discussed, so as to provide a theoretical basis for enhancing salt-tolerance and increasing yield of C. bungei seedlings in salt-alkali land. The results showed that under 0.5% NaCl stress, the leaves of the two varieties of C. bungei seedlings showed different degrees of salt damage symptoms, and the leaf salt damage symptoms of C. bungei No.1 were more serious than those of 008-1. With the prolongation of stress time, the REC of the seedlings of the two varieties of C. bungei increased first and then decreased, Chl and RWC showed a decreasing trend, SS, SP, Pro and SOD showed a rising trend first and then decreased trend, and the REC of 008-1 was significantly lower than that of C. bungei No. 1. Chl, RWC, SS, SP, Pro and SOD were significantly higher than those of C. bungei No.1. According to the results of salt stress test, 008-1 with strong salt tolerance was selected to alleviate exogenous ABA. It was found that spraying exogenous ABA could significantly increase the seedling height and advance the germination of new leaves under salt stress, indicating that exogenous ABA could alleviate the effect of salt stress on the growth of C. bungei to some extent. At the same time, spraying exogenous ABA reduced the relative electrical conductivity of leaves of C. bungei seedlings under salt stress, increased the contents of Chl, RWC, SS, SP , Pro, and the activities of antioxidant enzymes SOD, POD and CAT, and promoted the accumulation of endogenous hormones IAA, ABA,GA3 and ZR. The results indicated that exogenous ABA could alleviate osmotic stress induced by salt stress, and improve the antioxidant enzyme activity of C. bungei seedlings, and promote the regulation of endogenous hormone content in plants. In conclusion, salt stress inhibited the growth of C. bungei seedlings, and spraying exogenous ABA at an appropriate concentration could alleviate the salt damage to a certain extent, with the concentration effect of 25 mg/L.