This is a really good example of how nutrient deficiencies can occur.
If you look at the parsley you can see the cotyledons turning reddish and the true leaves are lime green. This is the beginning of nitrogen deficiency.
What is causing the nitrogen deficiency - the fungus using all available N to break down organic matter in the potting soil.
The solution, add in some more nitrogen to get the plants going and allow the fungus breakdown the organic matter faster. The after a few months when the organic matter is decomposed, the nutrients locked up in the fungus will be released for the plant to use.