采用叶面喷施的方法,研究了0(CK)、150、300 和450 mg·L^-1 纳米SiO₂ 对髯毛箬竹(Indocalamus barbatus McClure)叶片净光合速率、气孔导度、蒸腾速率、胞间CO₂ 浓度、气孔限制值和水分利用效率等光合特征参数日变化(7:00 至16:00)的影响。结果表明:对照组髯毛箬竹叶片的净光合速率、气孔导度、蒸腾速率和气孔限制值的日变化曲线均为“双峰”型,有明显的“午休”现象;胞间CO2 浓度的日变化曲线则为“W”型;水分利用效率的日变化曲线为“U”型。与对照相比,喷施150、300 和450 mg·L-1 纳米SiO₂ 均能不同程度提高髯毛箬竹叶片的净光合速率、气孔导度和蒸腾速率,减小气孔限制值及胞间CO₂ 浓度的变化幅度,提高“午休”时的水分利用效率,缓解光合作用的“午休”现象;其中,300 mg·L^-1 纳米SiO₂ 处理组的效果最佳,在出现最大峰值的10:00 时300 mg·L-1 纳米SiO2 处理组的净光合速率、气孔导度和蒸腾速率分别比对照提高了13. 98%、71. 21%和49. 09%,且均与对照差异显著(P<0. 05)。综合分析结果说明:髯毛箬竹叶片光合能力的提高是气孔和非气孔限制因素共同作用的结果,而喷施适量的纳米SiO₂ 能够在一定程度上改善非气孔限制因素,从而增强髯毛箬竹叶片的光合能力。

Effects of 0 (CK), 150, 300 and 450 mg·L^-1 nano-SiO₂ on daily change (from 7:00 to 16: 00 ) of photosynthetic characteristic parameters including net photosynthetic rate, stomatal conductance, transpiration rate, intercellular CO₂ concentration, stomatal limitation value and water use efficiency of Indocalamus barbatus McClure leaves were researched by foliar spraying method. The results show that all daily change curves of net photosynthetic rate, stomatal conductance, transpiration rate and stomatal limitation value are “double peak”type and have obvious “midday depression”phenomenon, while those of intercellular CO₂ concentration and water use efficiency are “W”type and “U”type, respectively. Compared to the control, spraying 150, 300 and 450 mg·L^-1 nano-SiO₂ can increase net photosynthetic rate, stomatal conductance and transpiration rate with different degrees, decrease change range of stomatal limitation value and intercellular CO₂ concentration, improve water use efficiency at “midday depression”and relieve “midday depression”phenomenon of photosynthesis. In which, the effect of 300 mg · L^-1 nano-SiO₂ treatment group is the best, net photosynthetic rate, stomatal conductance and transpiration rate of this group increase by 13. 98%, 71. 21% and 49. 09% respectively to the control at 10:00 of appearing maximum peak value, and all of them have significant differences to the control (P<0. 05). The comprehensive analysis results show that the improvement of photosynthetic capacity of I. barbatus is caused by interaction of stomatal and non-stomatal limitation factors, while spraying appropriate amount of nano-SiO₂ can improve non-stomatal limitation factor to a certain extent, thus can enhance photosynthetic capacity of I. barbatus leaves.