Welcome to AFN. Before we can help you we'll need a lot more information. Some details on what is in your soil, what nutrients you are feeding and how often, the pH of your feeds and the pH of your run off. What kind of lights are you using, temperature and humidity of your grow area.
They could be underfed or possibly your pH is off and causing a nutrient uptake issue. One thing I do see is no perlite in your soil mix. Perlite is essential in a good soil mix to help keep the soil loose, hold water and nutrients, and to bring oxygen to the roots. It's possible your soil is compacting and cutting off needed oxygen.
The more information you can give us, the better we can help you.