Impact of phloem girdling on water status in desert plants Alhagi sparsifolia Shap. (Fabaceae) and Karelinia Caspica (Pall.) Less. (Asteraceae)

Abstract

The removal of a ring of phloem, named girdling, is used for manipulating carbohydrate content above and below the girdle. To investigate the impact of girdling on leaf water status, an experiment was carried out in Alhagi sparsifolia Shap. and Karelinia caspica (Pall.) Less., which grew in the Cele oasis-desert transitional zone with the treatment of control, semi-girdling (SG), and full-girdling (FG). The results showed that after 30 days of girdling, stomatal conductance (Gs), transpiration rate (Tr), root carbohydrate content, root respiration rate, leaf water content and leaf water potential decreased, and leaf carbohydrate content increased under the treatment of FG in two species. On the 1st day, almost all of the treatments showed no change in these parameters, except the full-girdled leaves in A. sparsifolia, which exhibited a reduction in Gs and Tr, and an increase in midday water potential. The treatment of SG showed a similar change to FG on the 30th day in A. sparsifolia; however, in K. caspica, there was no change on the 30th day of treatment. The result of the present work indicated that girdling decreases water status over a long time. Within a short time, however, girdling decreases the Gs and Tr, which lead to an increase in leaf water status in A. sparsifolia Shap. SG also decreased leaf water status over a long time in A. sparsifolia, but not in K. caspica. Most treatments of girdling decreased leaf water status over a long time, but not within a short time. Overall, girdling affects leaf water status, but it depends on time, species, and degree of girdling.