Yellowing and falling

Hi mate, the leaves yellowing and dropping from the bottom is usually nitrogen deficiency but at the stage you don't want a lot of Nitrogen. However I can see other issues like a little nute burn or possibly a zinc deficiency as that usually shows up as red burnt tips. I think your PH is the issue. Causing a slight lockout as you can see slight calcium and magnesium deficiency. Keep an eye on the PH and maybe do a slurry test to see where your soil is at. I hope this helps, good luck and happy growing