不同强度的红光和蓝光下菜豆叶片的荧光特性

Effects of different intensities of red or blue on chlorophyll fluorescence characteristics of bean leaves

关键词:  菜豆  光强  红光/蓝光  叶绿素荧光参数

Key words:  bean  light intensity  red/blue light  chlorophyll fluorescence parameters

摘要:

光质和光强均是影响植物光合作用的重要外部因素,该文以菜豆(Phaseolus vulgaris)为材料,通过叶绿素荧光技术比较研究了菜豆叶片在不同光强的红光和蓝光下叶绿素荧光特性的变化规律。结果表明:随着红光和蓝光光强的增加,菜豆叶片的光适应下的最大光化学效率(F_v'/F_m')呈下降趋势,但与在红光下相比,蓝光下叶片的F_v'/F_m'值较高。随着蓝光光强的增加,菜豆叶片PSⅡ实际光化学效率(Y(Ⅱ))和光化学猝灭系数(qP和qL)先呈上升趋势之后逐渐趋于平稳; 而随着红光光强的增加,以上参数呈下降趋势。随着红光和蓝光光强的增加,非光化学猝灭系数(NPQ)、相对电子传递速率(ETR)以及调节性能量耗散的量子产量Y(NPQ) 均呈上升趋势,但与在红光下相比,蓝光下叶片NPQ和Y(NPQ)的值较低,而ETR值较高。非调节性能量耗散产量Y(NO)随着红光光强增加而呈上升趋势,而随着蓝光光强增加呈下降趋势。综上可见,随着光强的增加菜豆叶片的光化学效率呈降低趋势,但叶片在蓝光下的光化学吸收和利用效率高于红光。研究结果可为植物对光强和光质的响应提供一定的参考。

Abstract:

Common bean is widely planted all over the world with a wide variety of ecological conditions. The photosynthesis of bean leaves varies remarkably under different ecological conditions which may be correlated to differing light quality and the light intensity. In order to study the effects of different intensities and qualities of the light on the photosynthesis of plant,bean(Phaseolus vulgaris)leaves were used as the material,and Pulse-Amplitude-Modulation chlorophyll fluorometer was used to record the changes of the chlorophyll fluorescence parameters with different light intensities of red or blue,primary leaves were offered to the treatments in the present work. The results showed that the maximum photochemical efficiency of light adaptation(F_v'/F_m',the efficiency of capture excitation energy in PSⅡ reaction center )decreased with the increase of light intensities of red or blue light,but the values of F_v'/F_m' under blue light were significantly(P<0.05)or very significantly(P<0.01)higher than those under the same intensities of red light. With the increase of light intensities of blue light,the actual photochemical efficiency of PS Ⅱ(Y(Ⅱ),the actual photochemical efficiency of PS Ⅱ under light)and the coefficient of photochemical fluorescence quenching(qP and qL,the proportion of reduction state of PS Ⅱ original electron acceptor-plastoquinone(Q_A)increased but became stable gradually,while the values of Y(Ⅱ),qP and qL decreased with the increase of red light intensities. These meant that the photosynthetic efficiency of bean leaves decreased with the increase of blue or red light intensities. Non-photochemical quenching coefficient(NPQ,the excess energy dissipation by PS Ⅱ antenna system),electronic transmission rate(ETR,ETR increases linearly with light intensity,until it reaches a maximum. This happens when the capacity of all electron sink is reached),and quantum yield of regulated energy dissipation[Y(NPQ),an important indicator of self protection and the ability of PS Ⅱ to deal with excess light energy] increased with the increase of blue light or red light intensity. Compared to under red light,the values of ETR under blue light were higher but the values of NPQ and Y(NPQ) were lower. Quantum yield of non-regulated energy dissipation[Y(NO),the proportion of excess light energy in the form of heat and fluorescence,one of the important indicators of light damage] increased with the increase of red light intensity but decreased with the increase of blue light intensity. These results showed that the photosynthetic efficiency of bean leaves decreased with the increase of light intensities,but the absorbing and utilizing efficiencies of blue light were higher than those of red lights. We believe that this work would be helpful in developing current understanding on the responses of plants to different light intensities and qualities.