What are the symptoms of sulfur deficiency in flowers? How to prevent and cure it?

The sulfur-deficient tender leaves yellowed from the leaf veins to the yellowing of the whole leaves, and the root system developed abnormally. Iron deficiency ranges from tender leaves to yellowing of old leaves. The prevention and control methods of sulfur deficiency and iron deficiency can be sprayed with 0.30% ferrous sulfate solution for 3 times in a row, each time with an interval of 1 week. At the same time, 0.20% urea hot metal solution can be used for extra-root topdressing.