关键词: 脐橙, 次生果黄化, 植物矿质营养缺乏症, 柑桔类果树

Abstract: The researches demonstrate as follows; the mineral nutrition content Ca, N in young fruit of Robertson's navel orange tree, grafted high five years ago, is more than, even much more than that of the same tree, grafted.high three years ago. As regards the mineral nutrition content K in these two kinds. of trees, the proportion is just inverse. If the former is compared with the latter, except P, the other ingredients such as Mg, Fe, Mn, Cu, Zn all possess a rising tendency. After Robertson's navel orange graftiong in that very year, the content of soluable carbohydrate in its fine root is obviously lower than that of the contract. High, rate of the yellowing secondary fruit falling of the first bearing fruit tree after grafting is closely concerned with Ca nutrition disturbance. Decreasing supply of soluable carbohydrate makes the root system degenerate and the new-born root system being restrained. This is an important factor, resulting in Ca nutrition disturbance.

Key words: NAVEL ORANGE, XANTHOCHROISM OF SECONDARY FRUIT, PLANT MINERAL NUTRITION DEFICIENCY DISEAES, ORANGE TREES