## 3 Results
### Morphological Structure of Leaf from Girdled Bearing Branches at Different LFRs  
The cell morphology and structure of the walnut leaves differed among the LFRs. The walnut fruits entered the rapid growth stage and the walnut leaves reached maturity after 30 days of LFR treatment. The mesophyll PT cells were long, columnar, rich in chloroplasts, and neatly arranged. The gaps between the mesophyll PT cells were small, and the cells were arranged in two layers in the leaf. In contrast, the chloroplast content of the sponge tissue was lower, the cell morphology was irregular, the cell arrangement was loose, and the gaps between cells were was large. The morphological structures of the leaf cells differed among the LFRs. The LT in the (1-2)L:(1-3)F treatments was smaller than in the other treatments, and the PT in these treatments was mostly double-layered, accounting for less than 1/2 of the LT. The PT cells were only arranged in a single layer in some areas, with fewer chloroplasts, and the leaves were lighter at LFRs of (1-2):(1-3) compared with those for the other LFRs (Figure 3A,B,F,G,K,L). The LT in the (3-5)L:(1-3)F treatments was larger, and most of the palisade structure in the leaf was double-layered, accounting for more than 1/2 of the LT, at LFRs of 1-2:1-3 than for the other LFRs. The (4-5)L:(1-2)F treatments resulted in PT cells in some parts of the leaves; the cells were tightly arranged, the number of chloroplasts was high, and the leaf color was darker than for the other LFRs (Figure 3C-E, H-J, M-O). A lower leaf-to-fruit ratio or a higher fruit load hindered leaf growth and development. The walnut fruit was ripening, and the leaves entered senescence after 90 days of LFR treatment. The leaf color markedly lightened, and the morphological cell structure was considerably different. The morphological structure of the leaf cells substantially differed among the LFR treatments. The leaves in the (1-3)L:(1-3)F treatments more quickly senesced, some of the UE cells were distorted and deformed, some mesophyll cells disintegrated, cavities appeared in the ST area, more free and damaged cells were observed in the mesophyll cells, and the lower epidermal cells disintegrated, bulged and fractured (Figure 4A-C,F-H,K-M). However, leaf senescence was not observed in the 5L:1F and 4L:1F treatments (Figure 4D,E); the ST area contained no cavities, and the epidermal cells showed no protrusion fractures. Leaf senescence was noted on the (4-5)L:(2-3)F branches. The upper epidermal cells were partially distorted and deformed, and the individual mesophyll cells began to disintegrate. A small number of cavities were observed in the ST areas of the leaves. Free damaged mesophyll cells were noted, and the LE cells were distorted and  
Figure 2: Comparison of anatomical structure in leaf structure on girdled bearing branches at different LFRs. (**A–E**) The differences in leaf thickness (LT), palisade tissue thickness (PTT), sponge tissue thickness (STT), upper epidermis thickness (UET), and phloem area of main vein (MVPA) between treatments. Note: Different lowercase letters denote significant differences (\(p<0.05\)) between treatments for the same index. deformed; however, no convex fractures were observed (Figure 4I,J,N,O). A lower LFR or a higher fruit load accelerated leaf senescence. The main vein in mature leaves developed into the xylem, and the cells were large and radially arranged according to the microscopy observations. The phloem was composed of multiple layers of smaller cells (Figure 5). The larger the LFR, the more developed the main vein of the leaves. The lengths of the main vein and main vein vascular bundle were significantly higher in the high-LFR than in the low-LFR groups (\(p<0.05\)). Figure 6 shows that the vein was longest at an LFR of 5:1 and significantly longer than that at the other LFRs (\(p<0.05\), Figure 6A). The vein was the shortest at 1L:3F, being significantly shorter than that at the other LFRs (\(p<0.05\)). The leaf vein was widest at 3L:2F and most narrow at 1L:2F (Figure 6B).