The Effects of Phloem Girdling on Leaf Cell Physiology and Chlorophyll Biosynthesis in Peach Tree

Abstract

Phloem girdling is used for many fruit trees to promote fruit set and quality. Although many studies showed the pomological and biochemical effects of girdling in fruit trees, there is very little information on how girdling affects cell physiology. The current study aimed to characterize the leaf xylem structure, cortex cell division, and expansion affected by trunk girdling during phloem healing in peach. The experiment was carried out on a two-year-old peach cv. Rich May grafted onto Garnem grown in 10 L pots in greenhouse. The girdling was performed on the trunk end of the May. The leaf samples were collected 1, 2, 3 and 4 weeks after treatment (WAT). The study showed that the girdling decreased tree growth, stomatal conductance and stomatal density. Girdling decreased chlorophyll biosynthesis in peach leaves. Furthermore, girdling treatment increased leaf cell expansion, xylem thickness, and xylem conduit number during two weeks. The results have demonstrated that leaf anatomy changed by girdling during phloem healing.