盐碱互作胁迫对高丹草叶片叶绿素荧光参数的影响

为明确高丹草Sorghum bicolor×S.sudanense在盐碱互作胁迫下的生理响应及耐受特点,以两种中性盐NaCl和Na_2SO_4以及两种碱性盐Na_2CO_3和NaHCO_3按不同比例配成50、100、150和200mmol·L~(-1) 4个盐浓度,并且每个盐浓度分别设7.0、8.0、9.0和10.0共4个pH梯度的盐碱互作组合,研究了在盐碱互作胁迫对高丹草叶片的叶绿素荧光参数的影响。结果表明,高丹草叶片的各生理参数受高盐浓度以及溶液中各离子浓度的影响较大,其中影响较大的为CO_3~(2-)浓度和总盐浓度。低盐浓度下,不同pH对高丹草叶片叶绿素荧光参数的影响相对较小,并且低于100mmol·L~(-1)的盐浓度下高丹草叶片PSⅡ反应中心的光化学活性无明显影响,即高丹草具有一定的抗盐碱性能力。但在高盐高pH条件下,高丹草叶片PSⅡ光化学效率的降低,并且此时随着pH的增加,高丹草叶片的PSⅡ反应中心活性降低幅度增大。高丹草在一定碱性盐浓度范围内可以通过提高非化学淬灭系数(NPQ)及时耗散过剩的光能,但在高盐浓度下高丹草叶片通过NPQ来耗散过剩光能的保护能力下降,并且高pH下降低幅度更为显著。盐和pH对高丹草叶片的各生理参数影响过程中存在明显的交互作用,并且随着盐浓度的增加,交互作用逐渐变大,即低盐浓度下,受pH的影响相对较小,但随着盐浓度的增加,pH的影响变大。高丹草叶片具有一定的耐盐碱能力,但在盐浓度较高地区推广高丹草要注意碱化度的影响。

Effects of salt and alkali interaction stress on chlorophyll fluorescence in leaves of Sorghum bicolor ×S.sudanense

In order to identify the physiological responses and tolerance characteristics of Sorghum bicolor × S.sudanense under salt and alkali interaction stresses,chlorophyll fluorescence parameters were measured in the leaves.Four salt stresses,50,100,150,and 200 mmol · L-1,were prepared by mixing the neutral salts NaCl and Na2SO4 and the alkaline salts Na2CO3 and NaHCO3.In addition,4 pH levels,7.0,8.0,9.0,and 10.0,were used for each salt stress treatment.The analyses showed that physiological parameters in S.bicolor × S.sudanense leaves were significantly affected by high salt and ion concentrations in the solution and by the concentration of CO3 2 and total salt concentration.At a low salt concentration,the effects of different pH values on chlorophyll fluorescence parameters were relatively small.When the salt concentration was ＜100 mmol · L-1,the photochemical activity of the PS Ⅱ reaction center showed no obvious effect indicating a certain resistance to salt and alkali.But under high salt concentration and high pH conditions,the PSⅡ photochemical efficiency decreased.In addition,the decrease in activity of the PS Ⅱ reaction center in S.bicolor ×S.sudanense leaves increased with increasing pH values.S.bicolor × S.sudanense can dissipate excess light energy in a restricted range of salt concentrations by improving non-photochemical quenching (NPQ).However,under high salt concentrations,the protective ability of excess light energy dissipation by NPQ decreased and was further decreased by high pH values.The effects of salt and pH values on physiological parameters in S.bicolor× S.sudanense leaves showed clear interactions.These interactions increased with the increase in salt concentration,indicating that the influence of pH value was relatively less at low salt concentrations,but the pH effect was greater with the increase in salt concentration.The photosynthetic ability of the S.bicolor ×S.sudanense leaves showed some tolerance to saline and alkali,but the degree of alkalization needs to be taken into consideration when considering growing these plants in high salt concentration areas.