I have noticed that my fig plants who naturally have thicker stems, are the ones that produce, and produce at a younger age, I was wondering why do some fig plants develop a thick stem, which usually ends up with figs on it, rather than the rest of my plants with very thin, non-productive stems. 
Plants at nurseries are always short and thick, and already have figs on them, they say they are only 1 year old, but my one year old plants are half the thickness of their stems, and do not have fruit!
Are there anyways to make your plant have thicker stems and shoots?

Aeilee

The nursery plants have been pruned to keep them small in the greenhouses. The apical stem is removed and the branch below is trained to becomes the apical (main) stem. this retards actual growth and height of the plant, this may be done several times before the plant is sold (shipped).

If cuttings are pruned to a single stem (kept from branching) you can get height and an increased caliper on the main stem. I have a seven (7) foot , 3/4 -1 inch caliper White Marsailles from last year that I pruned to a single stem. It will be air layered and pruned to final shape this year. Note different varieties have different growth rates.

that gives me an idea. i might try for bonsai with Niagara Black. good looking leaves, good tasting figs.. in miniture.

Thanks Pete S for this good info. I will be trying this on my new cuttings that I got last week. They are doing good in there new home.

Zone 8
South West TX