What is the richest source of Golden Rice?

Excuse me, I've been hearing a lot about Golden Rice lately and its potential benefits in addressing nutritional deficiencies. Could you please elaborate on what exactly is the richest source of Golden Rice? Is it a particular type of soil, a specific cultivation method, or perhaps a certain region where it is grown that contributes most significantly to its golden hue and nutritional value? I'm quite curious to understand the factors that make it so rich in beta-carotene and other nutrients.