干旱胁迫对持绿性高粱光合特性和内源激素 ABA、CTK含量的影响

【目的】研究干旱胁迫对不同持绿性高粱光合特性以及叶片和根系中内源激素含量的影响，为高粱持绿性资源的发掘和应用提供理论依据。【方法】采用盆栽试验的方法，选用持绿性高粱B35和非持绿性高粱三尺三为试验材料，设置无干旱胁迫（土壤含水量为田间最大持水量的75%-80%）和干旱胁迫两种水分处理（土壤含水量为田间最大持水量的45%-50%），分别在开花期和灌浆期进行干旱胁迫，研究干旱胁迫下不同持绿性高粱光合作用、叶绿素荧光特性以及叶片和根系中内源激素（脱落酸和细胞分裂素）含量的变化，并分析干旱胁迫下叶片和根系中内源激素含量的动态平衡以及叶片中内源激素含量与光合特性参数间的相关性。【结果】开花期和灌浆期干旱胁迫均抑制了不同持绿性高粱的光合作用，但干旱胁迫下B35的叶绿素含量（Chl）、光合速率（Pn）、气孔导度（Gs）、光系统Ⅱ（PSⅡ）的初始叶绿素荧光（Fo）、最大光化学效率（Fv/Fm）、光化学淬灭系数（qL）以及电子传递速率（ETR）的降低幅度均明显小于三尺三；且在灌浆期三尺三Chl的衰减程度更为明显，Pn的下降程度也更大。同时，干旱胁迫使三尺三在灌浆期PSⅡ反应中心结构受到了损害或失活。开花期和灌浆期干旱胁迫提高了不同持绿性高粱根系和叶片中脱落酸（ABA）的含量，B35叶片和根系中ABA含量的增幅显著高于三尺三，且在灌浆期的增幅更大；干旱胁迫降低了不同持绿性高粱根系和叶片中细胞分裂素（CTK）的含量，三尺三根系和叶片中CTK含量的降低程度明显高于B35，且在灌浆期减幅更大。B35和三尺三叶片中ABA的含量高于根系，CTK的含量低于根系；干旱胁迫降低了叶片和根系中CTK/ABA的比值，并且在开花期和灌浆期B35的降低程度均大于三尺三。ABA含量与Pn呈显著负相关，与ETR呈极显著负相关；除Fo外，CTK含量与Gs呈显著正相关，与Chl、Pn、Fv/Fm、qL和ETR呈极显著正相关。【结论】干旱胁迫下，持绿性高粱比非持绿性高粱具有较高的叶绿素含量和光合能力。ABA和CTK共同作用调控气孔的运动，并影响光合速率及光合电子传递等其它光合生理过程。

Effects of Drought Stress on Photosynthetic Characteristics and Endogenous Hormone ABA and CTK Contents in Green-Stayed Sorghum

【Objective】The objective of the experiment was to investigate the effect of drought stress on photosynthetic characteristics and contents of endogenous hormones and to provide a scientific basis for exploring and utilizing the stay-green sorghum. 【Method】 A pot-grown experiment was conducted with green-stayed sorghum (B35) and non-green-stayed sorghum (Sanchisan) as materials with two water treatments including non-drought stress (75%-80% of the field moisture capacity) and drought stress (45%-50% of the field moisture capacity) at anthesis stage or grain filling stage, respectively. Photosynthesis, chlorophyll fluorescence and endogenous hormone contents including abscisic acid (ABA) and cytokinin (CTK) both in leaves and roots were examined under drought stress. In addition, the dynamic balance of endogenous hormone contents in leaves and roots and the relationship between photosynthetic characteristics and endogenous hormone contents in leaves under drought stress were analyzed. 【Result】 Photosynthesis of the two different stay-green sorghum materials were restrained by drought stress at both anthesis stage or grain filling stage, however, the chlorophyll contents (Chl), photosynthetic rate (Pn), stomatal conductance (Gs), PSⅡ original fluorescence (Fo), maximal photochemical efficiency (Fv/Fm), photochemical quenching (qL) and electron transport rate (ETR) of B35 decreased significantly less than those of Sanchisan under drought stress. At filling stage, in Sanchisan, the decrease of Chl under drought stress was more obvious, and Pn decreased markedly, which might be resulted from damage or inactivity of the structure of PSⅡreaction centre. Drought increased ABA contents in leaves and roots of the two different stay-green sorghum cultivars. ABA contents in leaves and roots of B35 increased significantly greater than those in Sanchisan especially at grain filling stage. While drought decreased CTK contents in leaves and roots of the two different stay-green sorghum cultivars. CTK contents in leaves and roots decreased significantly greater than those in B35 especially at grain filling stage. ABA contents of B35 and Sanchisan were higher in leaves than in roots, while CTK contents were the opposite. CTK/ABA both in leaves and roots decreased under drought stress, and the reduction extents in B35 were greater than those in Sanchisan at both anthesis stage and grain filling stage. Moreover, ABA contents were negatively related with Pn at 0.05 level and with ETR at 0.01 level, and CTK contents were positively related with Gs at 0.05 level and with Chl, Pn, Fv/Fm, qL and ETR at 0.01 level.【Conclusion】 Stay-green sorghum has higher chlorophyll contents and photosynthetic capacity than non green-stayed sorghum under drought stress. Interaction between ABA and CTK influences the movement of stomata and other related physiological process regarding photosynthesis such as Pn and ETR.