How can I increase the rootstock of a lemon tree?
Rootstock of Lemon Tree
I apologize, but I'm not exactly clear on what information you're looking for. If you mean that you want to develop a healthy root system on a lemon tree, following good cultural practices involving correct watering, light, soil, and fertilizer will result in a healthy tree, and that means healthy roots. This article has more information: https://www.gardeningknowhow.com/edible/fruits/lemons/how-to-grow-a-lemon-tree.htm