In my yard are two Owari Satsuma Mandarin trees. They were planted at the same time, sometime in the seventies. They came from the same source, a farmer who intended to plant an orchard but lost financing and ended up selling off the trees.
One tree is planted on the east side of the house about five feet from the wall. The other, planted on the west side of the house, is about four feet west of the driveway. Neither gets supplemental water and probably never has, nor are they ever fertilized.
The tree on the east side of the house produces fruit with a thin, tight rind that peels cleanly, leaving very little pith. Fruit from the tree on the west side of the house has a thick, puffy, loose rind that leaves a lot of pith when peeled.
The fruit from the tree on the east side of the house is sweeter than the fruit from the tree on the west side.
Within thirty-five feet of the east side tree is a navel orange and a grapefruit tree. The west side tree is fifty feet from those trees and eighty feet from a lemon tree in a yard further to the west.
The tree on the east side is not shaded from the east and gets full pre-noon sun. The tree on the west side is fifteen feet from the house next door, aligned with the back wall, and gets a lot of sun throughout the day.
What could account for the differences in the fruit from the two trees?