How to improve on avocado cultivation?

On April 19, 2017, our technician specialized in the cultivation of avocado moved to the area of Ribera Alta (Valencian Community) to visit an avocado planting of 250 trees that since planting had no vegetative development.
During the visit our technician observed that the seedlings had very short branches and a very fair number of leaves.

Here is a real example of how to get it:

http://www.edypro-online.com/integral-plans-by-crops/integral-plans-by-crops_1/cultivazione-of-avocado