Brown/yellow/purple leaves in

Loons like you hit it 2nhard with nutrients that's what caused the discoloration along the leaves veins. This seems to be fairly old. There is also leaves that arenstarting to fade naturally. Some of the lower leaves are looking bad cause the plant is useing up old energy stored in the lower leaves. You can probably give it a top dressing of some fresh spil and work casting and kelp meal should be enough to hold it over for the last week or so. You can get away with doing nothing you will be fine aswell. I would personally keep giving it nutrients and then flush the soil real good a few days b4 harvest