The study looked at how onion plants grow and take in nutrients to help farmers know when to fertilize. They found that nitrogen and potassium are absorbed most during the early growth stage, while phosphorus and sulfur are taken up more during flower formation. Nutrients like nitrogen, phosphorus, potassium, and sulfur move from the leaves to the flowers as the plant grows. Other nutrients like zinc, copper, manganese, and iron are absorbed continuously. This information can help farmers plan when to add fertilizer to get more nutrients and better harvests.