Foliar Carbon Isotope Composition (δ13C) and Water Use Efficiency of Different Populus deltoids Clones Under Water Stress

Abstract

Foliar carbon isotope composition (δ¹³C), total dry biomass, and long-term water use efficiency (WUE_L) of 12 Populus deltoids clones were studied under water stress in a greenhouse. Total dry biomass of clones decreased greatly, while δ¹³C increased. Single-element variance analysis in the same water treatment indicated that WUE_L difference among clones was significant. Clones J₂, J₆, J₇, J₈, and J₉ were excellent with high WUE_L. Extremely significant δ¹³C differences among water treatments and clones were revealed by two-element variance analysis. Water proved to be the primary factor affecting δ¹³C under water stress. It showed that there was a good positive correlation between δ¹³C and WUE_L in the same water treatment, and that a high WUE_L always coincided with a high δ¹³C. δ¹³C might be a reliable indirect index to estimate WUE_L among P. deltoids clones.