Global agriculture must increase crop production while ensuring the sustainable use of available resources. Improving crop productivity depends not only on the genetic potential of crops but also on the efficient production, translocation and utilization of photoassimilates within the plant. The source?sink relationship plays a vital role in regulating crop growth, yield and quality. The source, mainly mature green leaves, produces carbohydrates through photosynthesis, while the sink includes developing grains, seeds, fruits, roots and tubers that utilize or store these assimilates. Maintaining a proper balance between source capacity and sink demand ensures efficient dry matter partitioning and higher harvestable yield. Agronomic practices such as balanced nutrient management, optimum plant population, efficient irrigation, foliar nutrition, canopy management and the use of plant growth regulators help improve source efficiency and sink strength. In addition, breeding approaches aimed at enhancing photosynthetic efficiency and sink capacity offer new opportunities for sustainable yield improvement. Thus, effective source?sink management enhances resource-use efficiency, improves crop productivity and quality and contributes to long-term food and nutritional security.