The researchers studied how different levels of nitrogen and potassium fertilizers affect the growth of capsicum plants in a poly house. They tested various combinations of nitrogen and potassium levels to see which one resulted in the highest nutrient uptake by the plants. The experiment showed that applying 180% of the recommended nitrogen and 100% of the recommended potassium led to the highest uptake of nutrients by the capsicum plants at all growth stages. This means that using these specific fertilizer levels can help capsicum plants grow better and absorb more essential nutrients.