盐、碱胁迫对燕麦幼苗光合作用的影响

摘要

以砂培‘定莜6号’燕麦幼苗为材料，研究不同浓度 NaCl 和 NaHCO3（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 NaCl 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（qP）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 NaHCO3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、qP 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，NaHCO3胁迫的燕麦幼苗叶片叶绿素含量、Pn、Gs、Tr、Fv ／Fm、ΦPSⅡ、qP 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 NaCl 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 NaCl or NaHCO3 levels (0,50,100,150,200 mmol·L -1)for 4 days,and the effects of NaCl and NaHCO3 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 NaCl stress,the chlorophyll con-tents,net photosynthetic rate (Pn),stomatal conductance (Gs),transpiration rate (Tr),PSⅡ maximum photochemi-cal efficiency (Fv /Fm),actual photochemical efficiency (ΦPSⅡ),photochemical quenching (qP),and Hill reaction activity were decreased significantly with increasing concentration of NaCl,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 CO2 concentration (Ci)decreased and then increased.(2)When oat seedling were treated with NaHCO3,the chlorophyll contents,Pn,Gs,Tr,Ls,Fv /Fm,ΦPSⅡ,qP and Hill reaction activity significantly de-creased,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 NaHCO3 concentration.(3)At the same concentration of Na +, the degree of decrease in chlorophyll content,Pn,Gs,Tr,Fv /Fm,ΦPSⅡ,qP and Hill reaction activity and increase in NPQ,Y(NPQ),Y(NO),(β/α-1),(A +Z)/(V +A +Z)were higher in NaHCO3 tress than in NaCl stress.These findings indicate that the injury by alkali stress to photosynthetic system of oat seedlings was greater than that by salt stress.