The effects of irrigation schedule on photosynthetic characteristics and quality biological characteristics during different growth stages of isatisindigotica were studied in Yimin Irrigation District of Gansu Province in 2016. With the normal water condition in seedling stage and fleshy root maturity stage

the photosynthetic physiological characteristics and quality of Isatis were measured under mild

moderate and severe water deficit treatments in vegetative stage and fleshy root growth stage. The results showed that the leaf net photosynthetic rate (Pn)

stomatal conductance (Gs) and transpiration rate (Tr) of Isatis were decreased most significantly for Moderate and severe water deficit in vegetative nd fleshy root growth stages

and with the higher degree of water deficit

the greater the decrease. The comprehensive quality of WD5 was the best

the Indigo

Indirubin and (R

S)-goitrin contents of WD5 were 9.1%

5.3%

9.1% higher than CK respectively

quality of other treatments were improved moderately with the increasing in mild water deficit

but severe water deficit was not conducive to the accumulation of active ingredients. Therefore

water deficit?of Isatis under mulched drip irrigation reduced Pn

Gs and Tr

improved the water use efficiency

and mild-to-moderate water deficit was helpful to improving the quality of Isatis.