How to judge which kind of nutrition flowers lack by leaves

Judge what kind of nutrients flowers lack by their leaves:

① symptoms first appeared in the old leaves, indicating that plants lack chlorine, phosphorus, potassium, magnesium, zinc and so on. Symptoms first appear in the new tissue, indicating that plants lack calcium, iron, boron and so on.

When ② was deficient in fluoride, the whole sandalwood plant was dark green, the petiole turned purple, the growth was retarded, the old leaves had no spots, but the veins appeared yellow, and the leaves were easy to fall off.

When ③ is deficient in potassium or zinc, yellow, brown and purple spots appear on the old leaves (depending on the flowers), the leaf tip curls downward, the leaf turns yellow from the edge to the center, but the leaf vein is still green, the leaf edge curls upward or downward, and the leaf wilts gradually.

When ④ is boron-deficient or calcium-deficient, symptoms begin to appear in the new leaves, which can easily lead to the death of terminal buds.

When ⑤ is deficient in iron, the young leaves show yellow and white, and the veins are still green, but the leaf margin will wither gradually over time.