鄱阳湖苦草及马来眼子菜PSⅡ荧光参数对水深变化的光响应

Light-response of PS Ⅱ fluorescence parameters on Vallisneria natans and Potamogeton malaianus to various water depths in Poyang Lake

关键词:  苦草, 马来眼子菜, 水深, 叶绿素荧光, 光响应曲线

Key words:  Vallisneria natans, Potamogeton malaianus, water depth, chlorophyll fluorescence, light-response curve

摘要:

以典型沉水植物苦草和马来眼子菜为材料, 利用水下饱和脉冲调制叶绿素荧光仪研究不同水深(0.5、1.0、1.5、2.0、2.5 m)对两种植物叶片最小荧光(F_o)、最大荧光(F_m)、 PSⅡ最大光化光效率(F_v/F_m)、有效量子产量[Y(Ⅱ)]、光化学淬灭系数(qP)、非光化学淬灭系数(qN)、非调节性能量耗散的量子产量[Y(NO)]等荧光参数的影响。结果表明:水深1.5～2.0 m处苦草生物量最大,而1.0～1.5 m处马来眼子菜的最大; 两种植物的F_o均先降低后升高,而荧光参数[(F_m、F_v/F_m、F_v/F_o、Y(Ⅱ)、qP]均先升高后降低; 2.0 m处苦草的F_v/F_m、F_v/F_o最大,1.5 m处马来眼子菜的最大; 相同水深下,马来眼子菜的qN比苦草低,与qP变化趋势相反; 苦草的Y(Ⅱ)最大值出现在水深1.5～2.0 m内,马来眼子菜的Y(Ⅱ)最大值出现在1.5 m处; 两者的Y(NO)随水深变化均表现出显著差异,过高或过低水深均抑制植物生长; 相对光合电子传递速率(ETR)在不同水深处理间均差异显著,苦草的最大ETR比马来眼子菜小,说明其有较强的耐弱光能力。综上所述,在水深1.5～2.0 m苦草光合能力最强,最适宜生长; 水深1.0～1.5 m最适宜马来眼子菜生长。

Abstract:

In order to study the effects of water depth on the chlorophyll fluorescence characteristics of typical submerged macrophyte, Vallisneria natans and Potamogeton malaianus were selected as test materials in Poyang Lake wetland. Water levels(0.5,1.0,1.5,2.0,2.5 m)were controlled by buckets, minimum fluorescence( F_o), maximum fluorescence(F_m), the maximum actinic light efficiency of PS Ⅱ(F_v/F_m), effective quantum yield [Y(Ⅱ)], photochemical quenching coefficient(qP ), non-photochemical quenching coefficient(qN ), unregulated energy dissipation quantum yield [Y(NO)] were measured by a submerged, modulated fluorescence spectrometer(Diving-pam). The variation of each parameter with depths was explored. The results showed that the maximum biomass of Vallisneria natans appeared in 1.5-2.0 m water depth, and that of Potamogeton malaianus appeared in 1.0-1.5 m water depth. F_o of each macrophyte decreased first and then increased, while the fluorescence parameters [F_m, F_v/F_m, F_v/F_o, Y(Ⅱ), qP] all increased first and then decreased. F_v/F_m and F_v/F_o of Vallisneria natans reached the maximum under the condition of 2.0 m, but the maximum of Potamogeton malaianus appeared at 1.5 m. At the same depth, qN of Vallisneria natans was lower than that of Potamogeton malaianus. The change trend of qP was reversed. The maximum Y(Ⅱ)of Vallisneria natans appeared in the range of 1.5-2.0 m water depth, but for Potamogeton malaianus, it appeared at 1.0-1.5 m. Y(NO) showed significant differences with changes of water depths, too high or too low water depth all inhibited plant growth. The relative photosynthetic electron transport rate(ETR)was significantly different between different water depth treatments. The maximum ETR of Vallisneria natans was smaller than that of Potamogeton malaianus which indicates that it has strong resistance to weak light. In summary, under the condition of 1.5-2.0 m water depth, Vallisneria natans has the strongest photosynthetic capacity and can grow the best, and Potamogeton malaianus is the most suitable for growth in 1.0-1.5 m.