Athosanswered grow question 6 years ago A 7 week plant in a 1 gallon pot? you are way overdue a transplant (2 weeks overdue I would think), and the soil is fairly depleted of nutrients. I'm not so sure it's Nitrogen deficiency, since the yellowing is not homogeneous and those dark spots make me think more like a Potassium (K) deficiency.
Anyway, if you want to keep them in a 1 gallon pot, you would need to feed early.