Why, when laying potato tubers for storage, does their weight decrease by spring?

1) During storage, living cells breathe (or, tuber cells breathe)
2) In the process of breathing, starch breaks down into glucose, glucose is oxidized to carbon dioxide and water, which evaporate.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.