The researchers studied how to grow potatoes with more selenium, a nutrient important for health. They sprayed two types of selenium on the plants at different stages of growth. They found that one type of selenium worked better than the other in increasing the total amount of selenium in the potatoes. The best time to spray the selenium was during the stage when the potatoes were growing bigger. The potatoes treated with the better selenium type had more inorganic selenium, while both types had a lot of a specific selenium compound called selenomethionine. This study suggests that spraying the better selenium type during the potato bulking stage can help produce potatoes rich in selenium.