由于脐橙对环境条件的要求比一般柑桔品种高 ,较丰产的脐橙品系在我国的甜橙适宜区、次适宜区栽培 ,幼果的生理落果也很严重 ,着果率不高。而一些产量本来就不高的脐橙品系 ,即使在我国甜橙最适宜区栽培 ,着果率也很低 ,难以达到经济产量。因此 ,我国大部分地区栽培脐橙仍须通? As the requirements of environmental conditions orange than the average citrus varieties, more abundant navel orange lines in China’s sweet orange suitable area, sub-suitable for cultivation, young fruit physiological drop is also very serious fruit rate is not high. However, some navel orange lines, which are not high in yield, even have the most suitable areas for cultivation of sweet orange in our country. Fruit yield is also very low and it is difficult to achieve economic output. Therefore, most parts of our country still need to pass through the cultivation of navel orange?