Turmeric powder, leaves and whole turmeric root is offered to various Hindu deities and is an essential part of many Hindu worship. The turmeric powder is not offered to Shiva – it is not sprinkled or poured on the Shivling. But turmeric is offered to Gauripatta or jaladhari, the base of Shivling.
The upper part of Shivling represents Shiva and he represents masculinity and therefore is not offered turmeric.
The Gauripatta represents Goddess Parvati and is feminine and is offered Turmeric. It is offered as a cosmetic product to the Goddess.
This is not based on any scriptures but it is purely a tradition followed by people based on regional beliefs.
The rule might not be applicable in all regions.
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