模拟酸雨胁迫下硅对髯毛箬竹光合特性的影响

以髯毛箬竹为试验材料，研究了模拟酸雨胁迫(pH 3.0)下硅对髯毛箬竹叶片叶绿素相对含量、光合作用日变化以及叶绿素荧光特性等的影响.结果表明:20和100 mg·L^-1 Na₂SiO₃预处理可以不同程度地抑制酸雨胁迫下髯毛箬竹叶片叶绿素含量的显著下降，且以100 mg·L^-1浓度处理效果最佳，叶绿素含量可提高22.7%，而高浓度(500 mg·L^-1)预处理则无缓解作用-酸雨胁迫下，髯毛箬竹光合“午休”现象加重，日平均净光合速率(P_n)、气孔导度(G_s)和气孔限制值(L_s)明显降低，而胞间CO₂浓度(C_i)增大，经过20～100 mg·L^-1硅预处理后，P_n、G_s、L_s不同程度增加，而C_i有所降低，且以100 mg·L^-1硅预处理效果最佳，日平均P_n增加39.2%.酸雨胁迫下，箬竹PSⅡ最大荧光(F_m)、最大光化学效率(F_v/F_m)、潜在活性(F_v/F_o)、有效光化学效率(F_v′/F_m′)、最大荧光产额(F_m′)、光化学淬灭系数(q_P)、非光化学淬灭系数(q_N)、PSII实际光化学效率(Φ_PSⅡ)降低，暗适应和光适应下的最小荧光产额F_o、F_o′ 则升高；而100 mg·L^-1硅预处理明显抑制了胁迫下各荧光参数的变化，F_v/F_m、F_v/F_o、F_v′/F_m′和Φ_PSⅡ分别增加35.2%、146.2%、55.0%和24.3%.说明外源适宜浓度硅预处理能有效地缓解酸雨胁迫导致的髯毛箬竹光合活性下降和光合系统损伤，从而提高胁迫下植物的光合能力.

Effects of silicon on photosynthetic characteristics of Indocalamus barbatus under simulated acid rain stress.

With Indocalamus barbatus as test material, the effects of silicon on the relative content of chlorophyll, diurnal variations of photosynthesis, and chlorophyll fluorescence were examined under simulated acid rain (pH 3.0) stress. The results showed that under acid rain stress, 20 and 500 mg x L(-1) of Na2SiO3 could prohibit the decrease of the relative content of chlorophyll to some extent; 100 mg x L(-1) of Na2SiO3 could get best effect, with the relative chlorophyll content being 22.7% higher than the control; while 500 mg x L(-1) of Na2SiO3 didn't have any effect. Under the stress, the midday depression of photosynthesis became more serious. The average daily net photosynthetic rate (Pn), stomatal limitation value (Ls), and stomata conductance (Gs) were all decreased significantly, while the intercellular CO2 concentration (Ci) increased. After treated with 20-100 mg x L(-1) of Na2SiO3, the Pn, Ls, and Gs increased to some extent while Ci decreased, and 100 mg x L(-1) of Na2SiO3 was most effective, with the average daily Pn increased by 39.2%. The maximum fluorescence of dark adaptation (Fm), maximal photochemical efficiency (Fv/Fm), potential activity (Fv/Fo), effective photochemical efficiency (Fv'/Fm'), maximum fluorescence of light adaptation (Fm') of PSII, photochemical quenching (qp), non-photochemical quenching (qN), and actual photochemical efficiency of PSII (PhiPSII) were all decreased obviously under simulated acid rain stress, but the minimum fluorescence of dark adaptation (Fo) and the minimum fluorescence of light adaptation (Fo') increased. 100 mg x L(-1) of Na2SiO3 could restrain the changes of fluorescence parameters obviously, with the Fv/Fm, Fv/Fo, Fv'/Fm' and PhiPSII increased by 35.2%, 146.2%, 55.0% and 24.3%, respectively, compared with the control. It was suggested that applying appropriate concentration of exogenous silicon to I. barbatus could efficiently relieve the decrease of its photosynthetic activity and the damage of its photosynthetic system caused by acid rain, and thus, improve its photosynthetic ability under the stress.