How many linkage group are present in a plant 2n = 24?

The number of linkage groups in diploid plants with chromosome number 24 will be 12. $$\left( {\frac{{24}}{2} = 12} \right).$$
Linkage, as related to genetics and genomics, refers to the closeness of genes or other DNA sequences to one another on the same chromosome. The closer two genes or sequences are to each other on a chromosome, the greater the probability that they will be inherited together.
They are inherited as a group during cell division, they act and move as a unit rather than independently.