Answer:
It's not the amount of DNA that determines the size of chromosomes in a specie but the amount of genetic information that is needed to be stored may be loosely (more euchromatin) and densly tight (more heterochromatin). For example, Potato and Chimpanzee share sma enumber of 48 chromosomes but as a mammal with complex organization, a chimpanzee's chromosomes are highly densely packed as compared to that of potato that stores only potato level information.
