The amount of DNA in an organism is not necessarily correlated with its size. While a kiwi and a strawberry may be similar in size, they belong to different plant families and have different amounts of DNA. Generally, plants can have highly variable amounts of DNA, which is influenced more by factors such as their species and chromosome numbers than by their physical size.
For example, kiwis (genus Actinidia) and strawberries (genus Fragaria) have different genomic structures and sizes of their genomes. In fact, many plants can have polyploidy—having multiple sets of chromosomes—which can significantly affect the total amount of DNA, regardless of the plant's size. Therefore, it's unlikely that a kiwi and a strawberry of the same size would have about the same amount of DNA.