Question: query regarding how to use the zinc sulphate in tomato and oher vegetables. 
Answer: -- please use zinc sulphate 2-3 gram/liter of water as a folier after 1 months of planting 3 times once in a week in the eveing time in the absence of rain. 

you can also  use oher vitamins such as tracel/mohaphol 2ml/liter of water once at vegetative stage, once at flowering stage and once at fruit setting stage in the evening time in the absence of rain.