Effects of Uniconazole on Photosynthetic Characteristics of Dahlia pinnata Cav.under Drought Stress

[Objectives]This study was conducted to explore the physiological mechanism of uniconazole in response to drought stress in Dahlia pinnata.[Methods]With potted seedlings of D.pinnata variety‘Danbanhuang’as an experimental material,the effects of different concentrations(10,20,30 and 50 mg/L)of uniconazole on the photosynthetic characteristics of D.pinnata under drought stress and rewatering conditions were discussed.[Results]With the extension of drought time,the chlorophyll SPAD value,net photosynthetic rate,transpiration rate,and stomatal conductance of each treatment group decreased significantly,while the intercellular CO_(2)concentration showed a trend of first decreasing and then increasing;and after pretreatment of uniconazole spraying on leaves,it could alleviate the inhibition of drought stress on the photosynthesis of D.pinnata,and was beneficial to the recovery of photosynthetic capacity of D.pinnata after rewatering,and the effect of leaf application concentration of 30 mg/L was the best.It showed that exogenous uniconazole helps to improve the drought resistance of D.pinnata.[Conclusions]This study provides a new experimental basis for the chemical regulation of stress resistance in D.pinnata and its production and application.