Oranges suffering from Zn-deficiency often result in chlo rosis in the intei’-veinal ateas of the leaf, and it can be eliminated by sprinkling zinc fertilizer After studying with an electronic microscope the ultrastructures of the orange leaves Iccking zinc and those sprinkled with zinc fertilizer, we discover. (1) The major characteristics of leaf calls of Zn-deficient plants are that the cytoplasm, the endoplasmic reticulum and the ribosomes are poor, and that there are generally big starch grains in the chloroplasts. (2) After the sprinkling of zinc fertilizer, the structure of leaf cells returns to normal; the [cytoplasm is rich, the amount of chloroplast increases, and a lot of rough endoplasmic rgticulum with various shapes in the cytoplasm can be found. Furthermore, the complented Zinc can promote the photosynthesis of Zn-def icient plants and improve their N-metabolism, so that the yield of the fruit can be increased and the quality improved