Help little problem ?

Hi guys just noticed some yellowing on some leaves at the bottom of my plants only a few have this and i dont know what it could be the lights are the correct distance from the plants and the humidity and temps are good sitting around 76 temp and 48% humidity but they are 39 days old as of today and they aint really had much nutes only had 2 feeds but i was worrying about getting nute burn so they only had 1/4 dose then since then i have only fed them plain PH'ed water im wondering can they yellow from lack of nutes? thanks any help is welcomed , KC

The 2nd picture is the worst leave of all the plants theres only that one like that , thanks

Can anyone help me out please? could the yellowing be because they aint really had nutes ?

Yes, they likely need N. But pic of the whole plant and a better idea of what you are growing in would help.

Hey thanks for the reply growindad if u go on my profile the other post was yesterdays pictures thanks again , KC

They look pretty good in those pics to me! I am guessing you have a nuted soil and it has run out. You also seem to be a couple weeks into flower? I would dose with some grow nutes for a week or two and then move to flower oriented. But I am no expert!

nope there still in veg my friend roughly 6 weeks not switched them yet and i think im going to start with the nutes on there next feed , thanks KC