Notices how the leaves are twisting. Then in the third pic the tips are drooping down. Also notice the slightly yellow stem in the third. The plants are 16 days old.
Errr.... I wouldnt worry about those bottom leaves. They should be dying off eventually anyway. And thats not yellowing thats fresh baby green newgrowth give it a wiff it should smell like pure planty goodness.
i hate the smell of plants, when they 1st grow, Plant smell with the smalled touch of mJ. even after you pick them, ive had this plant picked and put in a airtight double sided plastic sheet. it still smells the same lol, more i smell it the better it smells.