This is a Flash Seeds Diesel Haze. (AF, Fem.) It's 15 days from being wet in towels. The plant seems to be yellow in the center. I'm also growing a Barney's Seeds Tangelo Rapido (also AF, Fem.)at the same time in exactly the same conditions and it's not doing this. The TR is also bigger than the Diesel Haze. Soil is Sunshine Mix #4. So far I haven't added any nutrients at all, just water. Yesterday the plant didn't look like this, so whatever is causing it started up quickly.

The only thing I could find on the GrowWeedEasy troubleshooting page that might look like this is sulfur uptake problems, but I haven't the faintest idea what I'm doing here (total beginner) so I thought I'd ask for some advice.
Thanks!

The only thing I could find on the GrowWeedEasy troubleshooting page that might look like this is sulfur uptake problems, but I haven't the faintest idea what I'm doing here (total beginner) so I thought I'd ask for some advice.
Thanks!