NEVER reduce Nitrogen in flowering.
All Nitrogen is to a plant, is protein.
Humans eat Protein, and our bodies turn it into Nitrogen. This is called being in Positive Nitrogen Balance. The opposite is b eing catabolic, which means youre using youre own muscle ect, for energy. Not good.
You plat has cannabilized the larger leaves looking for Nitrogen.
The correct ratio for weed is 1:1:2.
Weed basically like the same amount of Nitrogen, as it does Phosphorus, and 2x the amount of Potassiun vs N-P.
Tissue analysis says weed likes a 19.5-20-39 and adjusted PPM depending on stage of growth....... Some strains will also like a bit of extra Iron, but not all.
In an 8 weeks strain, the PPM of the base formula as in my case 19.5-20-39 is increased every week by a small amount until week 6. They also get a small weekly ever increasing amount of Magnesium/Sulfur. I use Epsom Salts. My formula also uses Calcium Nitrate for both Calcium, and Nitrogen. 15.5-0-0
In weeks 2.5-4 they get Mono Potassium Phosphate. 0-52-34. Bumping it up to 19.5-72-73. It is discontinued week 6
In weeks 5-6 they get extra Epsom Salts. In weeks 7-8 feed is reduced by 40%-60%.
Does it seem logical to limit PROTEIN when your plant will be making buds, stretching, and making all kinds of other chemicals??? I think not.
Remember all Nitrogen is, is Protein. Limit Protein when youre trying to grow, and you will not succeed.
I myself would for sure just give them a good base feeding with Nitrogen included at the same rate as Phosphorus. Do not over feed trying to make uo. The Nitrogen should help save some of the leaves. Just give a balanced feed.