The reason is right there in the article! For your edification;

A scorching heatwave has curtailed wheat output in India and domestic prices have soared to an all-time high.

"We were expecting curbs on exports after two to three months, but it seems like the inflation numbers changed the government's mind."

Rising food and energy prices pushed India's annual retail inflation up towards an eight-year high in April, strengthening economists' view that the central bank would have to raise interest rates more aggressively to curb prices.

Wheat prices in India have risen to a record high, in some places as high as 25,000 rupees (£263) per tonne, way above the government's fixed minimum support price of 20,150 rupees.

But a sharp and sudden rise in temperatures in mid-March means the crop size could be smaller than expected at about 100 million tonnes or even lower, a New Delhi-based dealer with a global trading firm told Reuters.

The government had estimated production would hit an all-time high of 111.32 million tonnes.

Not a fan of the PM, but the gazette calls out a couple of exceptions, including: "Export will also be allowed on the basis of permission granted by the Government of India to other countries to meet their food security needs and based on the request of their governments"

I presume the list is 0 length right now, and it'll be interesting to see if it ever expands.

The Dear Leader's grand pronouncements should never be taken at face value.