Step 1: Understanding the Concept:
Due to severe groundwater depletion caused by intensive rice-wheat cropping systems, the governments of Punjab and Haryana enacted water conservation laws in 2009.
Detailed Explanation:
- The Punjab/Haryana Preservation of Sub-soil Water Act, 2009 was enacted to prohibit farmers from transplanting paddy before a notified date (usually mid-June, such as June 15 or 20).
- Sowing paddy nursery is also restricted to early May.
- Delaying rice transplanting aligns the crop's peak water-demand phase with the onset of the monsoon rains. This significantly reduces the need for groundwater pumping during the hot summer months of May and June, when evaporation rates are extremely high.
- Therefore, the act's primary regulatory mechanism is to fix the permissible dates for sowing rice nurseries and transplanting rice in the states.
Step 2: Final Answer:
The correct option is Option (A).