Advances in irrigation technologies are crucial in addressing water scarcity and enhancing agricultural productivity. This systematic review evaluates the effects of precision irrigation systems, such as variable-rate irrigation (VRI) and smart irrigation systems, on plant physiology and crop yields. VRI, which adjusts water application based on spatial variability in soil and crop conditions, has been shown to improve water use efficiency by up to 27% and increase crop yields by 10-15%, especially in semi-arid regions. However, high installation costs, estimated at USD 50-100 per acre, and the need for specialized knowledge limit its large-scale adoption in developing regions. Smart irrigation systems, leveraging AI and IoT technologies, optimize irrigation schedules using real-time data from soil moisture sensors, weather forecasts, and crop growth models. Studies have demonstrated a reduction in water consumption by up to 35% while maintaining or increasing yields by 8-12%. Despite these advantages, the reliance on uninterrupted internet connectivity and the complexity of system management pose significant barriers, particularly in rural areas. Both systems have been shown to enhance root development, nutrient uptake, and overall plant health, leading to improved crop resilience to environmental stressors. On the downside, their implementation requires substantial initial investments, regular maintenance, and skilled labor, which can deter small-scale farmers. In conclusion, while modern irrigation technologies significantly contribute to sustainable water use and improved crop performance, widespread adoption remains a challenge due to economic and technical constraints. Future research and policy support should focus on making these technologies more accessible and scalable, particularly for resource-constrained regions facing the dual challenges of climate change and food security.