Option 1: 1954 - This option does not correspond with the correct answer of 1966. It is irrelevant to the period when there was a substantial increase in foodgrains production, specifically wheat production.

Option 2: 1964 - This option does not correspond with the correct answer of 1966. It is also irrelevant to the period when there was a substantial increase in foodgrains production, specifically wheat production.

Option 3: 1965 - This option does not correspond with the correct answer of 1966. It is also irrelevant to the period when there was a substantial increase in foodgrains production, specifically wheat production.

Option 4: 1966 - This is the correct answer. The question states that there was a substantial increase in foodgrains production, particularly wheat production, during a specific time period. This option aligns with that, indicating that the period of significant growth in production occurred after 1965.

Alert - correct answer should be 1966.