牛叠肚幼苗对盐碱胁迫的生理响应及其耐盐阈值

以盆栽牛叠肚组培苗为试材,比较研究了不同浓度中性盐(NaCl、Na2SO4)和碱性盐(NaHCO3、Na2CO3)胁迫对其生长和生理指标的影响。结果显示:(1)牛叠肚幼苗生长在碱性盐(NaHCO3、Na2CO3)处理下表现出"低促高抑"现象,而在中性盐(NaCl、Na2SO4)处理下均受到不同程度的抑制。(2)随着盐碱胁迫浓度的升高,牛叠肚叶片的相对电导率呈增加趋势,丙二醛(MDA)积累波动变化;Na2SO4和NaHCO3处理下二者之间的变化趋势相似,而NaCl和Na2CO3处理下二者之间变化趋势则不同。(3)牛叠肚叶片中超氧化物歧化酶(SOD)活性随胁迫浓度增加先升高后下降,而过氧化物酶(POD)活性呈先下降后升高趋势,说明牛叠肚主要通过SOD和POD的互补作用来降低氧化伤害。(4)以相对株高生长量下降50%为标准,求得牛叠肚幼苗对NaCl、Na2SO4、NaHCO3、Na2CO34种单盐的耐受阈值分别为85.18(0.50%,W/V)、40.77(0.58%,W/V)、171.00(1.44%,W/V)、114.20(1.21%,W/V)mmol·L-1。研究表明,各盐碱胁迫使牛叠肚幼苗的生长受到不同程度的抑制,但其在一定浓度范围内通过提高抗氧化酶(SOD、POD)活性来减轻盐碱伤害,维持植株的正常生理代谢;牛叠肚幼苗对碱性盐(NaHCO3、Na2CO3)的耐受能力强于中性盐(NaCl、Na2SO4)。

Physiological Response of Rubus crataegifolius Bge.Seedlings to Saline Stress and Its Salt Tolerance Threshold

The effects of saline stress(NaCl,Na₂SO₄,NaHCO₃ and Na₂CO₃) with different contents on the growth and physiological indexes in pot-cultured Rubus crataegifolius seedlings were studied.The results showed that:(1)The growth of R.crataegifolius seedlings was promoted by NaHCO₃ and Na₂CO₃ under lower salinity,and inhibited under higher level.It was inhibited by NaCl and Na₂SO₄ under different salinity.(2)With the saline stress rising,the relative electric conductivity was increased,and the malondiadehyde(MDA) accumulation fluctuated.The changed trend between the two indexes was similar under Na₂SO₄ and NaHCO₃ stress,and it was different under NaCl and Na₂CO₃ stress.(3)The SOD activity increased and then decreased with increasing salinity,while,POD activity decreased then increased,which showed that it mainly depended on the SOD and POD complementary action to reduce oxidative damage.(4)The salt tolerance thresholds for R.crataegifolius seedlings were 85.18(0.50%,W/V),40.77(0.58%,W/V),171.00(1.44%,W/V) and 114.20(1.21%,W/V) mmol·L^-1,when taking 50% drop in relative height growth as the standard.As a consequence,the growth of R.crataegifolius seedlings was restrained under different salinity-alkalinity stress,but they could adjust themselves by increasing the activities of protective enzymes(SOD,POD) to reduce the salt injury under a certain saline conditions,and maintain the normal physiological metabolism of plant seedlings.The R.crataegifolius seedlings tolerance ability to alkaline salt(NaHCO₃ and Na₂CO₃) was stronger than that of neutral salt(NaCl and Na₂SO₄).