Thirty-four of Punjab's 117 assembly constituencies and four of its thirteen Lok Sabha seats are reserved for Scheduled Caste candidates, in proportion to the population share.
Reservation guarantees the identity of the representative and not the constituency of the vote. A reserved seat is contested by candidates of the mainstream parties, elected by an electorate in which Dalit voters are a large minority or a small majority, and the winner answers to a party rather than to that community.
That is the standard critique of reservation in Indian legislatures and it applies with particular force in Punjab, where the population share is highest and the political outcome is thinnest.
Punjab has had Scheduled Caste Chief Ministers briefly and has not had a sustained Dalit political leadership.
The most effective Dalit political action in Punjab in the last decade has been outside electoral politics: the land committee, the Ravidassia separation, and the dera followings.
This is the largest gap between demographic weight and political outcome in any Indian state.
Reservation attaches to the constituency and the constituencies are rotated at each delimitation, so a seat reserved now may not be reserved after the next exercise. A member cannot build a base in a seat that will be de-reserved under him, and the incentive runs directly against the long local presence the provision was meant to produce.
Reservation of seats has produced representation without producing a party of the community's own, which is the difference between Punjab and Uttar Pradesh.
The land question is why. In Punjab the Scheduled Caste population is overwhelmingly landless and the landholding community is the political base of both major parties.
Academic work on reservation and representation.