what relation did salt have in this protest?
It was a direct action campaign of tax resistance against the British salt monopoly
Salt March
The 25-day march lasted from 12 March 1930 to 6 April 1930 as a direct action campaign of tax resistance and nonviolent protest against the British salt monopoly. 
who did participated in dandi march from uttarakhand 79 Marchers; between the ages of 20 and 30 hailed from almost all parts of the country, accompanied Gandhi what is salt march? It was an act of nonviolent civil disobedience in colonial India led by Gandhiji
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Salt March [SEP] Introduction
The Salt March, also known as the Salt Satyagraha, Dandi March and the Dandi Satyagraha, was an act of nonviolent civil disobedience in colonial India led by Mohandas Karamchand Gandhi. The 25-day march lasted from 12 March 1930 to 6 April 1930 as a direct action campaign of tax resistance and nonviolent protest against the British salt monopoly. Another reason for this march was that the Civil Disobedience Movement needed a strong inauguration that would inspire more people to follow Gandhi's example. Mahatma Gandhi started this march with 79 of his trusted volunteers. Walking ten miles a day, the march spanned over 240 miles (384 km), from Sabarmati Ashram to Dandi, which was called Navsari at that time (now in the state of Gujarat).