I can't really diagnose anything, but to help the people who can I suggest a much closer picture, focusing on the problem area. And if you can use the flash on the camera, or another light source, it should come out more white balanced, everything looks yellowish in that picture but it's the light causing it. Which isn't to say your light is causing yellowing of the plants, just that in the picture it adds a yellow cast.
Last edited by AgentPothead; 09-06-2017 at 12:42 AM..
Reason: edited for clarity cause I'm a confusing stoner sometimes