What environmental change would not negatively affect plants and yet would require them to adapt?
Gravity.
Gravity is omnipresent, yet not essential for crop growth; on the contrary, in order to resist it, crops have to invest a great deal of nutrients to grow tall and sturdy, which supports their growth. Breeding in the void precisely eliminates this factor.
Of course, those strange fluctuations in the void are also a cause of mutation, breeding in the void tends to result in an especially high probability of producing bizarre varieties.
Mutations could be favorable or unfavorable; it suffices to discard the unfavorable ones, as they are mere vegetables and fruits, valued for growing quickly, having large yields, being tasty and nutritious.
Under Tom's meticulous care, a giant field of vegetables and fruits had emerged inside the grow sphere.
"You can even grow crops in the void? Is there any place you can't plant?" Negris was impressed.