Excuse me, teacher, what is the reason for this tomato?

The abnormal fruit of tomato is caused by bad weather during flower bud development. Being on the upper floor should be caused by the continuous rainy and cooling weather some time ago, especially the low temperature at night. Hard fruit is one of improper use of dipped anthers, and the other is untimely fertilization and insufficient nutrition supply. Seedlings like you should use potassium nitrate fertilizer or high potassium fertilizer containing a lot of elements to promote fruit growth and control the use of nitrogen fertilizer. Umbilical rot is a problem caused by physiological calcium deficiency. Poor root development, drought and water shortage will lead to insufficient calcium absorption. Spraying calcium amino acid or chelated calcium with cloud moss on the leaves for adjustment.