Na2SO4和Na2CO3胁迫下苦楝幼苗的形态及光合生理特性

Morphological and photosynthetic physiological characteristics of Melia azedarach seedlings under Na2SO4 and Na2CO3 stresses

为探索苦楝应对盐胁迫的响应机制,该文以1年生苦楝(Melia azedarach)实生苗为材料,在盆栽条件下设置中性盐Na 2 SO 4和碱性盐Na 2 CO 33个盐浓度(200、400、600 mmol·^L(-1))处理40 d,研究苦楝的抗盐碱水平及在不同程度盐碱胁迫条件下的生长及光合生理变化。结果表明:随着盐浓度的提高,苦楝的苗高、地径和生物量的增长量均呈现下降趋势,且碱性盐胁迫条件下降程度更大,盐胁迫提高苦楝的根冠比。处理10 d时,苦楝幼苗的所有光合指标随中性盐和碱性盐浓度的提高呈相似的下降特征,碱性盐胁迫条件下的降低幅度显著大于中性盐胁迫,且随处理时间的增加,中性盐和碱性盐处理下苦楝幼苗的净光合速率和蒸腾速率显著降低。随着盐浓度的提高,苦楝的叶绿素含量呈现下降趋势,200 mmol·^L(-1)盐胁迫对叶绿素含量影响较小,400、600 mmol·^L(-1)盐胁迫均对叶绿素含量有显著影响。600 mmol·^L(-1)碱性盐胁迫条件下,苦楝叶片相对电导率和饱和水分亏缺最高,显著高于其余处理。同等浓度下,碱性盐胁迫的苦楝叶片相对电导率和饱和水分亏缺显著高于中性盐胁迫处理。综上结果认为,苦楝具有一定的耐盐碱能力,碱性盐比中性盐对苦楝幼苗的影响更大。

To explore the response mechanism of Melia azedarach to salt stress and to provide reference for the application of M.azedarach in saline and alkaline areas.One-year-old M.azedarach seedlings grown in pots were used as materials,and subjected to sodium sulphate or sodium carbonate of three concentrations(200,400,600 mmol·^L(-1))for 40 d to study the growth,physiological and photosynthetic parameters.The results were as follows:The growth of seedling height,ground diameter and biomass showed downward trends with the increase of salt concentration under neutral or alkaline salt stress,and the decline was greater under alkaline salt stress.Salt stress increased the root to shoot ratio.On the 10th day,all photosynthetic parameters showed similar decline characteristics under neutral or alkaline salt stress,and the decrease extent under alkaline salt stress was significantly greater than those under neutral salt stress.With the increase of treatment time,the net photosynthetic rate and transpiration rate decreased significantly under neutral salt or alkaline salt.With the increase of salt concentration,the chlorophyll content showed a downward trend.Salt stress of 200 mmol·^L(-1)had little effect on the chlorophyll content,but 400 and 600 mmol·^L(-1)salt stress had significant effect on the chlorophyll content.Under 600 mmol·^L(-1)alkaline salt stress,the relative conductivity and saturated water deficit of M.azedarach leaves were the highest,significantly higher than those of other treatments.At the same concentration,the relative conductivity and saturated water deficit under alkaline salt stress were significantly higher than those under neutral salt stress.It can be seen that M.azedarach has a certain salt-alkali tolerance,the effect of alkaline salt on the M.azedarach seedlings is greater than neutral salt.