Why were the benefits of Green Revolution restricted to few

Why were the benefits of Green Revolution restricted to few states and few crops in initial stages of planning?

The Green Revolution implied use of High Yielding Varieties (HYVs)of seeds which required reliable irrigation and financial resources to buy better inputs. Because of this, the Green Revolution was restricted to the more affluent states of Punjab, Andhra Pradesh and Tamil Nadu. Further the use of HYV seeds primarily benefited the wheat growing regions only. Thus, the benefit of the Green Revolution was initially restricted to few states and the crops of wheat and rice only.