Answer:
Decrease in the current supply of wheat.
Step-by-step explanation:
If it is expected that the prices of wheat will increase in one month then this will lead to decrease the supply of wheat today. The producers wants to make more profits in the future by cut down the supply of wheat today because they'll get the higher prices for the same quantity of wheat after one month.
Hence, the producers will save some quantity of wheat for selling it in the near future.