Agro-physiological basis has a significant impact on crop plant growth and development in order to achieve higher yield. Physiological aspects of photosynthesis and respiration have to be demonstrated in sorting out the regulation and function of various components. If there are inefficiencies in these systems and if causes can be identified, they would represent legitimate targets for genetic manipulation. Properties of rubisco, alternative oxidase, and photorespiration process already loom as opportunities for genetic manipulation. However, about their utilities we are yet uncertain. Serious reinvestigation of foliage canopies offers promise for important gains in photosynthetic productivity of crops. Morphological traits associated with increased yield potential include grain number and harvesting index. Increased biomass to be associated with yield increases. Various physiological processes help in maintenance of growth, yield attributes and finally increase yield of cereals.