Problem with whats growing around it

[divaling]

Hi,
this is my third year of growing, I only grow 2 plants its just for my aches and pains and it seems I have to ask a question each year. So I'm in the UK I have to grow my 2 plants without bringing attention to them as its still a no no
here, I always grow in my pollytunnel and this year to make them less obvious I'm growing them behind the potatoes that I have in sacks, the heights just right to cover them. Sorry its a long story but I started the seeds off as usual and until now all was well, but suddenly the leaves on one have gone droopy and yellow, the top level is fine this is only on one plant the other is fine. What I'm wondering is if the potato plant could be causing a problem, its nearer to the droopy one. Any thoughts please could other type of plants make a reaction?

[divaling]

Hi everyone no replies from any of you yet and my poor plant looks quite ill so I now have pictures to show.
One picture is the sickly one, the other plant looks healthy and is right next to it, and the 3rd picture is to show
how the potatoes are right in front of them, wether thats making any difference I dont know, all are in pots in a pollytunnel. Do you think I should just scrap the sickly one or can it be brought back to life. Thanks for any advice.

[SoOrbudgal]

Looks overwatered don't see any air stones in that soil mix? It's up to you to salvage it seems like you know how to garden. Either way those roots are sick.