Tomato stress symptoms
I have some problems with my tomato plants (cultivar Moneymaker) that always develop the same stress symptoms around 24 days after you see the first seedlings emerging. Before that, they look healthy and fine. The symptoms start on the cotyledones and are then appearing on the older leaves (egdes of the lower leaf side get purple and there are yellow . Plants are growing in 1l of potting soil at 24°C-22°C and 70% relative humidity. The way the symptoms appear made me assume that it is a lack of one or more nutrients but that doesn't seem to be the problem. I tried different fertilizers (slow release, specific commercial tomato fertilizer, a general commercial fertilizer and half-strength hoagland solution) but with each of these fertilizers, the symptoms appear exactly at the same time as they do in unfertilized plants. There is also no difference in plant size, which makes me think that 1l of potting soil is providing them with everything they need at this growth stage. The rest of the conditions look pretty much normal and are used in many studies. I attached some pictures as well. Many thanks in advance.