Effects of nano-SiO_2 on daily change of photosynthetic characteristic parameters of Indocalamus barbatus leaves

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 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(P0.05).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.: nano-SiO2;Indocalamus barbatus McClure;photosynthetic characteristic parameter;daily change