What’s the reason for the leaf colours ?

Incorrect feeding and not watering enough to get adequate run off each time you irrigate. Plants showing signs of under feeding and burning from nutrient salt build up. A third of a litre (according to your diary) per plant is nowhere near enough. Pretty well too late to fix anything at this late stage.........had you asked some questions 3-4 weeks ago when these issues first started appearing, there may have been a chance to help them.