ive noticed the flavor get better on trees
after they have been in ground for a couple of years.
Also, i think flavor has a lot to do with minerals, soil, sun, moisture , other conditions...
i had gotten a cutting from a tree that the fruit didnt taste all that good.
the tree was fast growing and prolific, but the fruit was fairly small, and just marginal flavor.
i planted it to graft to it, but 1 graft didnt take, and the original tree is fruiting
and tastes very good now. The fruit is still fairly small, but i like the flavor.
i used a lot of compost, some iron and magnesium, and lots of leaf and woody mulch.
Also fish emulsion and worm castings.
i believe compost and mulch add to the beneficial bacteria and keep the soil cool,
keep grass and weeds away from the roots, and keep soil moisture even.
and this keeps the nematodes at bay.