Effects of water deficits on whole tree water use efficiency of orange.

Highlights: [•] We measured assimilation and transpiration simultaneously in whole orange canopies. [•] Water stress induces a non-significant increase in instant water use efficiency. [•] Water stress plants show higher water use efficiency at daily time scale. [•] The effect on daily WUE is due to different transpiration pattern under water stress. [•] Overall effect of water stress on water use efficiency resulted moderate in orange. [ABSTRACT FROM AUTHOR]