ok here is a bit on (n) nitrogen def.
nitrogen is most common def.
symptoms include slow growth.
lower leaves cannot produce chlorophyll and become yellow between the veins while the veins remain green.
yellowing progresses through the entire leaf eventually causing it to die and fall off.
stem's and the leaves undersides may turn reddish-purple,
but this can also be a sign of a phosphorous deficiency.

progression at a glance:
older leaves yellow between veins
older bottom leaves turn entirely yellow
more and more leaves yellow.severely affected leaves drop.
leaves might develop reddish-purple stems and veins on underside of leaf.
stealth, plz check the veins under leaves
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toxicity(overdose)
a overdose of (n) nitrogen will cause excessively lushfoilage that is soft and susceptable to stress including insect!! and fungal attacks.the stems become weak and they may fold over easy. the vascular tissue transport tissue breaks down,and water uptake is restricted.
In severe cases,leaves turn a brownish-copper color,dry,and fall off

the #3 picture are those leaves a blueish-green color ??
I emailed you the phosphorus deficiency " you've got mail" lol
oh ya these are quotes from book