盐、碱胁迫对燕麦幼苗光合作用的影响

Effects of salt and alkali stresses on photosynthesis in Avena nuda seedlings

以砂培‘定莜6号’燕麦幼苗为材料,研究不同浓度Na Cl和Na HCO3(0,50,100,150,200 mmol·L-1)胁迫对光合色素含量、气体交换、叶绿素荧光参数和叶黄素循环的影响。结果表明:(1)在Na Cl胁迫下,随着处理浓度增加,燕麦叶片叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学猝灭(q P)和Hill反应活力明显下降,非光化学猝灭(NPQ)、调节性能量耗散Y(NPQ)、非调节性能量耗散Y(NO)、激发能分配不平衡偏离系数(β/α-1)、叶黄素循环脱环氧化状态(A+Z)/(V+A+Z)显著提高,类胡萝卜素含量和气孔限制值(Ls)先升后降,胞间CO2浓度(Ci)先降后升。(2)在Na HCO3胁迫下,随着处理浓度增加,燕麦叶片叶绿素含量、Pn、Gs、Tr、Ls、Fv/Fm、ΦPSⅡ、q P和Hill反应活力显著下降,Ci、NPQ、Y(NPQ)、Y(NQ)、(β/α-1)、(A+Z)/(V+A+Z)明显增大,类胡萝卜素先升后降。(3)在相同Na+浓度下,Na HCO3胁迫的燕麦幼苗叶片叶绿素含量、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、q P和Hill反应活力下降及NPQ、Y(NPQ)、Y(NO)、(β/α-1)、(A+Z)/(V+A+Z)增加的幅度大于Na Cl胁迫。表明盐、碱胁迫均对燕麦幼苗光合系统造成了伤害,但碱胁迫的伤害程度大于盐胁迫。

New-released oat（ Avena nuda） cultivar ‘Dingyou No. 6＇seedlings were exposed to Hoagland nutrient solution with five Na Cl or Na HCO3levels（ 0,50,100,150,200 mmol·L-1） for 4 days,and the effects of Na Cl and Na HCO3 on photosynthetic pigment content,gas exchange and chlorophyll fluorescence parameters,and xanthophyll cycle in oat seedling leaves were studied by a sandy culture. The results showed：（ 1） Under Na Cl stress,the chlorophyll contents,net photosynthetic rate（ Pn）,stomatal conductance（ Gs）,transpiration rate（ Tr）,PSⅡ maximum photochemical efficiency（ Fv/Fm）,actual photochemical efficiency（ ΦPSⅡ）,photochemical quenching（ q P）,and Hill reaction activity were decreased significantly with increasing concentration of Na Cl,whereas the non-photochemical quenching（ NPQ）,regulated energy dissipation Y（ NPQ）,non-regulated energy dissipation Y（ NO）,the relative deviation（ β / α-1） from full balance between two photosystems,and the de-epoxidation extent of xanthophyll cycle（ A＋Z） /（ V＋A＋Z） were increased significantly,as well as the carotenoid content and stomatal limited value（ Ls） exhibited a humped-curve,the intercellular CO2concentration（ Ci） decreased and then increased.（ 2） When oat seedling were treated with Na HCO3,the chlorophyll contents,Pn,Gs,Tr,Ls,Fv/Fm,ΦPSⅡ,q P and Hill reaction activity significantly decreased,and the Ci,NPQ,Y（ NPQ）,Y（ NO）,（ β /α-1）,（ A＋Z） /（ V＋A＋Z） increased obviously except an humped-curve of carotenoid content with the increasing of Na HCO3 concentration.（ 3） At the same concentration of Na＋,the degree of decrease in chlorophyll content,Pn,Gs,Tr,Fv/Fm,ΦPSⅡ,q P and Hill reaction activity and increase in NPQ,Y（ NPQ）,Y（ NO）,（ β /α-1）,（ A＋Z） /（ V＋A＋Z）were higher in Na HCO3 tress than in Na Cl stress. These findings indicate that the injury by alkali stress to photosynthetic system of oat seedlings was greater than that by salt stress.