Profuse flowering and fruiting create high demand for a limited source of carbohydrates, which affects fruit set and development. These plenty number of flowers and fruits must be reduced to allow the trees to produce fruit that meets market expectations for size, color, and quality. The concept of source-sink relationship and the regulation of carbon partitioning in plants is useful for better understanding of crop physiology and the influence of yield-limiting factors on crop production. This relationship between source leaves and the various sink organs affects fruit production in not only the current season, but also the long term performance due to the perennial nature of fruit trees. Modeling early-season whole-tree carbohydrate supply and demand have greatly improved the understanding of the response of trees to manipulation strategies relating source-sink alliance. Various strategies have been adopted to manipulate sourcesink relationship like flower bud inhibition, flower thinning, fruitlet thinning, defoliation, girdling, pruning, application of hormones and nutrients, etc. Thus, a balance between vegetative and reproductive growth is an important aspect for improvement in yield and quality of fruit crops.