Indigo cultivation in India declined by the beginning of the 20th century because of its unprofitability in the world market because of new inventions.
European planters manufacturing indigo on colonial plantations in Bengal faced a major challenge from synthetic indigo. Synthetic indigo was a symbol of the successful integration of chemistry into industrial manufacturing that had occurred in the second half of the century, and it threatened to displace the colonial commodity.
It also fundamentally challenged the colonial program of “improvement” that agricultural indigo represented, and the mode of production consisting of stewardship of plants and the extraction of a commodity within the plantation system.