渗透胁迫对小麦幼苗叶绿素荧光参数的影响

用叶绿素荧光诱导动力学技术,研究模拟干旱条件对小麦幼苗叶片叶绿素荧光参数,即原初光能转化效率(F_v/F_m)、光合电子传递量子效率(φPSⅡ)、qP(光化学猝灭)、qNP(非光化学猝灭)、ETR(表观光合量子传递效率)的影响.结果表明,渗透胁迫对小麦幼苗叶绿素荧光参数影响较大.随着渗透胁迫的加剧,F_v/F_m和F_v/F_o都表现出现降低-增加-降低的趋势,在渗透胁迫2 h以前,小麦叶片内部没有发生光抑制,但随着胁迫的加剧,F_v/F_m值增加,使得小麦幼苗叶内发生光抑,导致ΦPSⅡ和ETR的下降;在渗透胁迫过程中,小麦叶片吸收光能的光化学猝灭(qP)的下降和光化学猝灭(qNP)呈现先降低后增加的趋势,说明小麦在受到干旱胁迫前期,PSⅡ反应中心的开放比例降低;在胁迫2h后,随着胁迫的加剧,qP和qNP增加有利于提高PSⅡ反应中心开放部分的比例,将更多的光能用于推动光合电子传递,提高了光合电子传递能力,同时非光化学能量耗散的提高,有助于耗散过剩的激发能,以保护光合机构,缓解环境胁迫对光合作用的影响,体现了小麦叶片的自我保护机制.两个品种相比,长武13的叶绿素荧光参数的变化幅度比陕253小,具有更强的抵御干旱胁迫的能力.

Effects of osmotic stress on chlorophyll fluorescence parameters of wheat seedling

By using chlorophyll fluorescence kinetics technology,this paper determined the chlorophyll fluorescence parameters F_v/F_m,ΦPSⅡ,qP,qNP,ETR of winter wheat seedling under simulated osmotic stress.The results showed that with the increase of osmotic stress,F_v/F_m and F_v/F_o had the trend of decrease-increase-decrease,indicating that photoinhibition did not happen at the first stage of osmotic stress,but the followed increase of F_v/F_m resulted in the photoinhibition and the decrease of ΦPSⅡand ETR.During the course of osmotic stress,qP and qNP decreased firstly and then increased,which was helpful to enhance the open ratio of PSⅡ reaction center,and made more photosynthetic energy use the photosynthetic electron transport to enhance the electron transport capacity.Meanwhile,the increase of non-photochemical quenching coefficient could be helpful to dissipate excess light energy,which protected the photosynthetic tissue,and mitigated the effect of environment on photosynthesis.All the results indicated that wheat seedling had its protection mechanism.Between the two test winter wheat varieties,Changwu 134 had a higher drought-resistance capacity than Shan 253.