State-run agencies have bought 11.92m tonnes of wheat from farmers so far this season, down 25% on the 15.92m tonnes bought in the same period a year ago
The attack was carried out by "Islamic State fighters", the group's Amaq news agency said.
In August, Islamic State claimed responsibility for an attack on a gathering of mourners at a hospital in Quetta that killed 70 people. But that attack was also claimed by Pakistani Taliban faction Jamaat-ur-Ahrar.