Abstract:

Foliar carbon isotope composition(δ¹³C), total biomass and long_term water use efficiency(WUE _L) of 12 Populus deltoides clones were studied under water stress in the greenhouse. Total biomass of clones decreased greatly while δ¹³C increased. The single element (clones) variance analysis and multiple comparison of WUE_L under same water treatment indicated that the difference between clones was significant, J₂, J₆, J₇, J₈, J₉ were excellent clones with high WUE_L. The significant differences between water treatments and clones were showed by two elements variance analysis of δ¹³C, and water was proved to be the primary factor which affected δ¹³C under water stress by the comparison of MS(Mean Square) and Fvalue. Under same water treatment, our results also indicated that there was a good positive correlation between δ¹³C and WUE_L, high WUE_L always went with high δ¹³C, and δ ¹³C may be a credible indirect index on estimating WUE_L between P. deltoides clones.

Key words: Populus deltoides, water stress, carbon isotope composition (&delta, ¹³C), total biomass, long-term water use efficiency(WUE_L)