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目的探讨干旱胁迫对草珊瑚叶绿素荧光特性及能量分配的影响,找到延缓干旱胁迫的方法,为抗旱栽培提供理论依据。方法考察15%PEG-6000模拟干旱胁迫条件下,经过不同浓度5-氨基乙酰丙酸(ALA)和不同时间处理后草珊瑚植株光合色素量、叶绿素荧光参数及能量参数等生理指标的变化。结果外源ALA显著提高了叶绿素a、叶绿素b、总叶绿素和类胡萝卜素的量,提高了最大荧光(Fm)、最大光化学效率(Fv/Fm)、光系统PSII潜在活性(Fv/Fo)、PSII有效光化学效率(Fv′/Fm′)、PSII实际光化学效率(ΦPSII)、光化学淬灭系数(qP)、电子传递率(ETR)和光化学速率(PCR)的水平,有效地降低了初始荧光(Fo),非光化学淬灭系数(NPQ)和热耗散速率(HDR),经过ALA处理后的光化学反应能量(P)所占比例显著升高,天线色素热耗散能量(D)和非光化学耗散能量(E)则表现出相反的趋势,并且P成为能量利用的主要途径,ALA促进了能量合理的再分配。结论 100 mg/L的外源ALA能够通过减少过剩激发能的耗散,提高光合电子传递效率,有效地缓解干旱胁迫对草珊瑚叶片PSII的伤害,提高植株的抗旱能力。
Aim To investigate the effects of drought stress on the chlorophyll fluorescence characteristics and energy allocation of S. australis and to find a way to delay the drought stress and provide a theoretical basis for drought resistance cultivation. Methods The changes of photosynthetic pigment content, chlorophyll fluorescence parameters and energy parameters under 15% PEG-6000 simulated drought stress were studied after different concentrations of 5-aminolevulinic acid (ALA) and different time treatments. Results Exogenous ALA significantly increased the contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid, and increased the maximum fluorescence (Fm), maximum photochemical efficiency (Fv / Fm), photosystem PSII potential activity (Fv / Fo) PSII effective photochemical efficiency (Fv ’/ Fm’), PSII actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (qP), electron transfer rate (ETR) and photochemical rate (PCR) Fo, non-photochemical quenching coefficient (NPQ) and heat dissipation rate (HDR), the proportion of photochemical reaction energy (P) after ALA treatment increased significantly, and the heat dissipation energy of antenna pigment (D) and non-photochemical Dissipative energy (E) shows the opposite trend, and P becomes the main way of energy utilization. ALA promotes the rational redistribution of energy. Conclusions Exogenous ALA at 100 mg / L can improve the photosynthetic electron transfer efficiency by reducing the dissipation of excess excitation energy, and effectively alleviate the damage of PSII in the leaves of A. przewalskii by drought stress and improve the drought resistance of plants.