干旱区生态环境知识资源中心

Leaf senescence can be described as the dismantling of cellular components during the terminal stage in the development of plant organs and tissues. In order to determine the leaf senescence process when stem girdling and leaf removal both exist. An experiment was carried out in Alhagi sparsifolia, which grew in the Cele oasis-desert transitional zone with the treatment of control (CK), phloem girdling (PG), leaf removal (LR), and combined girdling and removal (GR). Some parameters related to leaf senescence were measured at the 1st and 30th day post-girdling. The results showed that after PG and GR, leaf soluble sugar content, starch content, abscisic acid content, proline content, and malondialdehyde content increased substantially and leaf photosynthetic rate, stomatal conductance, transpiration rate, photosynthetic pigment content, and water potential decreased substantially compared with CK. It also changed much more in PG leaves than in GR leaves. The change in LR leaves was opposite to that of PG and GR leaves, but the change was rather slight. The result of the present work implied that senescence of leaves treated with PG greatly accelerates, and the accumulation of carbohydrates and ABA in leaves is probably the main reason for this. Separate LR could play a role in delaying leaf senescence in plants; however, this delay effect was not obvious. Nevertheless, partial removal of leaves led to a significant compensation of girdling effects, i.e., senescence will be delayed significantly in girdled leaves when treated with partial LR.