"I knew it, you dead skull; you're not at all interested in carrying out the God of Tree's task. You're just trying to create a rootstock to graft your crops onto," Negris said irritably.
Negris knew something was fishy. Not only was Ange not resisting the task given by the God of Tree, he was actively and happily engaging in it. Originally, Negris thought that Ange was excited about growing new things, but he underestimated him once again.
Ange wasn't interested in the task for the task's sake; it was purely because Kadiz had given him a plant capable of surviving in this environment and being cultivated into a rootstock.
A rootstock is a plant used for grafting. Some crops produce delicious fruit, but their roots are not well-developed, or their stems are too fragile, there are always various flaws. In such cases, the fruit-bearing branches can be grafted onto more robust plants, which are referred to as rootstocks.