As a young reproductive tree, when high levels of vegetative growth are still required for the tree to fill its allocated canopy space, but at the same time fruit production is necessary for economic reasons. As a mature tree, when the tree has filled its allocated space, and management is directed at suppressing excessive vegetative growth and increasing fruit production. Although trees rich in nitrogen have a wonderful dark green leaf colour, a common symptom is that fruit colour can be delayed and poor. This is especially so if large N applications have resulted in a potassium deficiency. Fruit yields are usually high in terms of numbers per tree, but fruit size is almost always smaller.
Fruit appear rougher, and have thicker rinds.
These in turn reduce the percentage of juice in the fruit. In some cultivars, sugar levels in the juice are lower. Typically a citrus tree produces three growth flushes in a season. Spring flush floral shoots are mostly produced on 12 month old wood, which means that the production of leafy spring shoots is critical for the following season's flowering and fruit set. On young trees, we should ensure that none of the flushes are lacking in nitrogen.