Manage nutrients properly is a specialist job. Fertilizers are only effective when applied in the correct way and at the right time. Processes in plants play a fundamental role in the uptake and efficiency of nutrients.
Growth = Photosynthesis - Respiration
Simply put, the difference between photosynthesis and respiration is growth. If a plant is able to produce more during photosynthesis than it consumes during respiration, it will grow. Growth is in fact an increase in dry matter (mass).
A quick recap. Photosynthesis is the name for the complex reaction which plants use to turn energy from the sun into sugars. In other words, the plant takes carbon dioxide from the air and water from the soil and combines them together to form carbohydrates (sugar). Oxygen is released as a waste product. Photosynthesis is dependent on temperature and light exposure. It occurs only during the day.
Plants (like humans) burn sugars and produce carbon dioxide in respiration. In addition to sugars, respiration also requires oxygen and water. Unlike photosynthesis, respiration does not require light. Respiration occurs in dark and light.