CAJ | 학술논문

利用PEG-6000模拟水分胁迫(ψs=-0.2MPa,胁迫时间:48 h,复水48 h),研究了紫花苜蓿(Medicago sativa L)品种陇东苜蓿和阿尔冈金叶片叶绿素荧光特性和光合色素含量的变化,旨在探讨紫花苜蓿水分胁迫条件下的光合反应机制.结果表明:光化学淬灭系数(qP)和PSII线性电子传递的有效量子产额(YIELD)以及非光化学淬灭系数(qN)和表观光合电子传递效率(ETR)在胁迫前后随光合有效辐射(PAR)的变化规律分别可用公式:Y=aLn(X)+b(Y:qP或YIELD,X:PAR,X≠0)和Y=aX2+bX+c(Y:qN或ETR,X:PAR)来表示;在受到干旱胁迫后,PSII最大光能转化效率(Fv/Fm)、PSII潜在活性(Fv/Fo)和光合色素含量均明显低于对照,在任意光强下的qP、YIELD和ETR值也极显著低于对照的相应值,qN值则极显著高于对照的相应值;同时,和对照相比,qN和ETR光响应曲线顶点所对应的光强值在受到胁迫后亦明显下降,表明光抑制初始点的降低和最大光保护能力的减弱,甚至光抑制的提前到来.干旱胁迫使得PSⅡ反应中心结构和功能遭到破坏而部分关闭,光合电子传递受阻,光能利用与光化学转化与能力下降,吸收的光能更多的以热能形式耗散.复水后,虽然有光保护机制的存在,但除陇东苜蓿光合色素含量及阿尔冈金类胡萝卜素外,各参数均未能恢复到对照水平,因此旱后复水不能完全解除干旱对PSII反应中心所带来的伤害.紫花苜蓿幼苗对干旱胁迫较为敏感.供试品种相比,陇东苜蓿耐旱性优于阿尔冈金.
이용PEG-6000모의수분협박(ψs=-0.2MPa,협박시간:48 h,복수48 h),연구료자화목숙(Medicago sativa L)품충롱동목숙화아이강금협편협록소형광특성화광합색소함량적변화,지재탐토자화목숙수분협박조건하적광합반응궤제.결과표명:광화학쉬멸계수(qP)화PSII선성전자전체적유효양자산액(YIELD)이급비광화학쉬멸계수(qN)화표관광합전자전체효솔(ETR)재협박전후수광합유효복사(PAR)적변화규률분별가용공식:Y=aLn(X)+b(Y:qP혹YIELD,X:PAR,X≠0)화Y=aX2+bX+c(Y:qN혹ETR,X:PAR)래표시;재수도간한협박후,PSII최대광능전화효솔(Fv/Fm)、PSII잠재활성(Fv/Fo)화광합색소함량균명현저우대조,재임의광강하적qP、YIELD화ETR치야겁현저저우대조적상응치,qN치칙겁현저고우대조적상응치;동시,화대조상비,qN화ETR광향응곡선정점소대응적광강치재수도협박후역명현하강,표명광억제초시점적강저화최대광보호능력적감약,심지광억제적제전도래.간한협박사득PSⅡ반응중심결구화공능조도파배이부분관폐,광합전자전체수조,광능이용여광화학전화여능력하강,흡수적광능경다적이열능형식모산.복수후,수연유광보호궤제적존재,단제롱동목숙광합색소함량급아이강금류호라복소외,각삼수균미능회복도대조수평,인차한후복수불능완전해제간한대PSII반응중심소대래적상해.자화목숙유묘대간한협박교위민감.공시품충상비,롱동목숙내한성우우아이강금.
Water stress mimicked by PEG-6000 solution (ψs =- 0.2 MPa, stress period 48 h, then rehydration 48 h) was performed on leaves of alfalfa (Medicago sativa L) varieties of Longdong and Algonquin seedlings. Chlorophyll fluorescence parameters and photosynthetic pigments concentration were measured. These measurements were used to investigate the available photosynthetic response mechanism to different water conditions. The results show that the change patterns of photochemical quenching (qP) and the effective quantum yield of PSII photochemistry (YIELD) with the increasing of the active radiation of photosynthesis (PAR) could be expressed by the equation:Y=a Ln(x)+b (Y:qP or YIELD, X:PAR,X≠0) and the change patterns of non-photochemical quenching (qN) and the relative electron transport rate (ETR) with the increasing of PAR could be expressed by the equation:Y=aX2+bX+c (Y:qN orETR, X: PAR). Significantly, the maximal photochemical efficiency of PSⅡ in the dark (Fv/Fm),potential activity of PSII (Fv/Fo)and photosynthetic pigments concentration in alfalfa leaves decreased obviously subjected to water stress. Simultaneously, the values of qP, YIELD and ETR in stress treatments were decreased significantly and the values of qN in stress treatments were increased obviously under every PAR. More particularly, the light intensities corresponding to the top point of light response curve of qN and ETR declined submitted to water stress. Compared to the controls, the initial point of photo-inhibition and the maximum photo-protection ability decreased, or photo-inhibition occurred in advance. It indicated that photosynthetic apparatuses and functions were inhibited by water stress, which weakened the light energy utilization and transform capability of PSII reaction center and light energy dissipated through heat energy mostly. After rehydration, all parameters except photosynthetic pigments concentration in Longdong and carotenoid in Algonquin partly recovered only to the level of the control though photo-protection might be triggered under water stress in alfalfa leaves. Therefore, rehydration did not countervail the damage induced by water stress in PSII reaction center completely. Alfalfa seedlings were sensitive to water stress, and the tolerance to water stress of Longdong was higher than that of Algonquin.