The root of the container is designed with a special coating. And the side wall of the container is concave and convex, and the outer top of the container is perforated. When the seedling root is outward and downward, it is in contact with the air (the small hole on the side wall) or any part of the inner wall, the root tip stops growing, Air pruning "and suppressing unwanted root growth. Followed by the root of the root of the germination of three or more than three new roots, continue to grow outward, the number of roots to 3 increments.