My aubergine plant seems to be developing some nutrient deficiency. I pulled it from the ground in autumn about 9 months ago and placed it into an air pruning pot with some potting mix, and kept it inside over winter. During this period it still flowered and produced several fruits which I consumed. The only issue were some spider mites which disappeared after spraying with neem oil.
I took it outside in spring after the last frosts, and it's started to flower again with fruits forming. I noticed a light aphid infestation today and sprayed with insecticidal soap. I've only fed it twice with a fish blood and bone mix, and general water with aquarium water.
I've noticed today that the older leaves are suffering with some interveinal yellowing, which seems to be starting from the middle and spreading out. Younger leaves are still green.
As aubergines go, this one is only 2 foot tall versus reaching the roof as with greenhouse grown plants.
Since the young leaves are not yet affected, is this more likely to be magnesium versus manganese or iron? pH is 7.4, and soil is moist.