Does aquaponics vegetables grow faster than soil grown vegetables?
First we need to understand one premise regarding plant development, and that premise is that plant yield is determined from genetics the plants receive from their parents. For example, if a lettuce has obtained genetics that have determined it will take 55 days for it to mature, then that will be the maximum uninterrupted potential for the lettuce. There's no nutrient, supplement, nor farming practice that can override the genetic make-up inside of that plant. There's nothing that you can do about it. The answer to your question is aquaponics vegetables do not grow faster than any other type of vegetables including soil and hydroponics, and vice versa.
It’s One Reason We Invented GMOs
What I will say is that humans are now capable of manufacturing and inserting gene codes that allow us to produce vegetables with certain traits. These are what we know as GMO products. This is not the same instance as described above regarding natural farming practices. GMO vegetables have foreign genes introduced into their DNA, which can modify a variety of characteristics ranging from disease resistance to heat tolerance. If their were a farming practice that could increase the yield of vegetables then I assume that GMO wouldn't be as prominent of a practice as it is today.
Aquaponics Provides A Better Environment
The job of the farmer really boils down to providing an optimal environment for the plant to grow. We are attempting to maximize its genetic potential and produce the best possible version of that crop. We do this by planting crops in correct seasons, reducing heat and cold loads, providing adequate nutrients, preventing pest, and much more. My stance is that aquaponics allows farmers to control and provide optimal plant environments better than any other farming practice. Aquaponics allows farmers to test nutrients and pH levels at a central location in the system to get an accurate understanding of the nutrient availability for all the plants. We know exactly how much nutrients each plant is receiving because they all use the same source of nutrients. In soil, testing the soil in one location will provide some insight on available nutrients, but not an accurate account due to different vegetables taking up nutrients at various rates. A lot of times in soil the plants are competing for nutrients in the same space. Competition for nutrients does have affects on the plant reaching its full potential. Aquaponics doesn't have these competitive factors, which is one of the key deliverables aquaponics provides to creating an optimal plant environment.