盐碱胁迫下燕麦幼苗生长生理差异及耐盐碱阈值

Physiological Difference and Saline-alkali Tolerance Threshold of Oat Seedlings under Saline-alkali Stress

为研究混合盐碱胁迫对燕麦幼苗生长、生理的影响,计算耐盐碱阈值,选用相对盐碱敏感品种‘白燕5号’和相对耐盐碱品种‘坝莜18号’为试验材料,设置不同浓度的盐碱胁迫处理,分析燕麦生长、生理指标的变化。结果表明:(1)不同浓度盐碱胁迫对‘白燕5号’和‘坝莜18号’幼苗的株高、根长和生物量有不同程度的抑制作用,分别在150 mmol/L和200 mmol/L胁迫时差异显著。(2)随着胁迫浓度的升高,‘白燕5号’SPAD值、P_(n)、G_(s)及T_(r)均呈下降趋势,在100 mmol/L胁迫时差异显著;‘坝莜18号’SPAD值、P_(n)、G_(s)、T_(r)则表现出先升后降的趋势,C_(i)呈先降后升的趋势,胁迫达到200 mmol/L时差异显著。(3)‘白燕5号’和‘坝莜18号’脯氨酸(Pro)和丙二醛(MDA)含量随着胁迫浓度的增加均呈上升趋势,过氧化氢酶(CAT)活性则呈相反趋势,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性呈先升后降的趋势,‘白燕5号’和‘坝莜18号’SOD活性分别在150 mmol/L和200 mmol/L胁迫时达到峰值且差异显著。(4)以株高较对照降低50%为标准,得‘白燕5号’和‘坝莜18号’幼苗对盐碱胁迫的耐受阈值分别为163.4 mmol/L和200.0 mmol/L。综上所述,燕麦幼苗混合盐碱耐受阈值的确定,可为盐碱地燕麦栽培与推广应用提供理论依据。

To investigate the effects of mixed salt-alkali stress on the growth and physiology of oat seedlings and to calculate the threshold of saline-alkali tolerance,two contrasting oat(Avena sativa L.)genotypes,‘Baiyan 5’(sensitive)and‘Bayou 18’(tolerant),were grown under a series of salt-alkaline concentrations,and a number of growth and physiological indicators were measured.The results indicated that(1)The plant height,root length,and biomass of the genotypes were differentially affected by the stresses,and the differences were statistically significant at 150 and 200 mmol/L.(2)The levels of SPAD,P_(n),G_(s),and T_(r) in‘Baiyan 5’decreased as the salt-alkaline concentration increased,and the decreases became statistically significant at 100 mmol/L.In contrast,the levels of SPAD,P_(n),G_(s),and T_(r) in‘Bayou 18’increased at low levels of salt-alkaline concentrations before they decreased at higher levels of concentrations,and the decreases became statistically significant at 200 mmol/L.Opposite responses to the increase of salt-alkaline concentrations was found for C_(i).(3)In both genotypes,the levels of proline(Pro)and Malondialdehyde(MDA)increased while that of catalase activity(CAT)decreased as the salt-alkaline concentration increased.The activities of superoxide dismutase(SOD)and peroxidase(POD)increased first to reach a maximum and then decreased as the salt-alkaline concentration increased.The maximum levels of SOD and POD were achieved at 150 and 200 mmol/L for‘Baiyan 5’and‘Bayou 18’,respectively.(4)The level of salt-alkaline concentration to reduce the plant height by 50% was proposed as the salt-alkaline tolerance threshold,which was estimated as 163.4 and 200.0 mmol/L for‘Baiyan 5’and‘Bayou 18’,respectively.In conclusion,the determination of oat seedling tolerance thresholds provides a theoretical basis for the cultivation and popularization of oats in salt-alkali soil.