盐胁迫下棉花幼苗叶片K^(+)、Na^(+)含量与光合参数的关系

The relationship between foliar K^(+) and Na^(+) concentrations and photosynthetic parameters of cotton seedlings under salt stress

为了解盐分胁迫下棉花叶片的K^(+)、Na^(+)含量与光合参数(净光合速率、最大羧化速率、最大电子传递速率、叶肉导度)之间的关系,设置4个盐分水平(50、100、150和200mmol·L^(-1))和对照处理,测定叶片的K^(+)、Na^(+)含量及光合参数。结果表明:棉花幼苗叶片的Na^(+)含量与盐分水平呈显著正相关,决定系数R^(2)为0.958,叶片K^(+)含量随盐分水平增加而降低,决定系数R2为0.871。此外,Na^(+)/K^(+)与盐分水平呈显著正相关。棉花叶片的K^(+)与Na^(+)含量表现为极显著负相关。叶片的Na^(+)含量与净光合速率、叶肉导度、最大羧化速率、暗呼吸速率、最大电子传递速率呈极显著负相关,相关系数分别为-0.878、-0.861、-0.835、-0.837和-0.813;叶片的K^(+)含量与净光合速率、叶肉导度、最大羧化速率、暗呼吸速率、最大电子传递速率呈极显著正相关,相关系数分别为0.718、0.735、0.645、0.856和0.603。当盐分水平为150 mmol·L^(-1)时,棉花叶片的K^(+)和Na^(+)含量分别为11.54和3.32 mg·g^(-1),是K^(+)、Na^(+)含量影响光合参数的临界值。研究结果为缓解盐分胁迫对植物造成的离子伤害提供重要参考。

To understand the relationships between leaf K^(+),Na^(+) concentration and photosynthetic parameters(net photosynthetic rate,maximum carboxylation rate,maximum electron transport rate,mesophyll conductance)in cotton seedlings under salt stress,we measured the concentrations of K^(+) and Na^(+) and photosynthetic parameters in cotton seedling leaves under four levels of salt stress(50,100,150 and 200 mmol·L^(-1))and control(0 mmol·L^(-1)).The results showed that there was a significantly positive correlation between foliar Na^(+) concentration and salt level,with a determination coefficient(R^(2))of 0.958.Foliar K^(+) concentration decreased with increasing salt levels,with R2 of 0.871.Moreover,the Na^(+)/K^(+) ratio was positively related to salt levels.There was an extremely significant negative correlation between K^(+) and Na^(+) concentration in the leaves.Foliar Na^(+) concentration was negatively correlated with net photosynthetic rate,mesophyll conductance,maximum carboxylation rate,dark respiration rate and maximum electric transport rate,with the correlation coefficients of-0.878,-0.861,-0.835,-0.837,and-0.813,respectively.Foliar K^(+)concentration was positively correlated with net photosynthetic rate,mesophyll conductance,maximum carboxylation rate,dark respiration rate and maximum electron transport rate,with the correlation coefficients of 0.718,0.735,0.645,0.856 and 0.603,respectively.Under the salt stress of 150 mmol·L^(-1),foliar K^(+) and Na^(+) concentrations were11.54 and 3.32 mg·g^(-1),which was the threshold of potassium and sodium ions affecting photosynthetic parameters.The results could provide an important reference for alleviating the ion damage on plants under salt stress.