Hi, Ahmad Ali.

Double haploid (DH) population is normally used to retain the desired alleles in the genome. In addition, the method is also a quicker way to produce homogenous line, instead of self-pollination over generations to produce inbred lines. Some researchers sequence DH materials to achieve a better assembly quality because of reduced genetic variants.

If you are aiming to map the QTL using F2 population with maximum polymorphism throughout the genome, then crossing between different DH individuals will give you the best result.

Hope this will help. 

Kindly see here..

http://www.biotecharticles.com/Genetics-Article/Mapping-Population-Types-and-Method-of-Production-3335.html

More to see..

https://books.google.co.in/books?id=YdOX0R8uUxgC&pg=PA29&lpg=PA29&dq=advantage+to+use+double+haploid+(DH)+population+for+back+crossing+instead+of+the+F1+population+to+the+recurrent+parents&source=bl&ots=SOzxht0rJ7&sig=2Y0UfUu_NoGBMvgrgxfTeLSr2HU&hl=en&sa=X&ved=0ahUKEwip7eGvnujTAhVBv48KHW4LCNMQ6AEILDAC#v=onepage&q=advantage%20to%20use%20double%20haploid%20(DH)%20population%20for%20back%20crossing%20instead%20of%20the%20F1%20population%20to%20the%20recurrent%20parents&f=false

To be explored..

https://books.google.co.in/books?id=nEFTZmvKdxsC&pg=PA25&lpg=PA25&dq=advantage+to+use+double+haploid+(DH)+population+for+back+crossing+instead+of+the+F1+population+to+the+recurrent+parents&source=bl&ots=mLzM7gf6_i&sig=iW3KFEaWDDuoiIL7mLiO0L2j9Og&hl=en&sa=X&ved=0ahUKEwip7eGvnujTAhVBv48KHW4LCNMQ6AEILzAD#v=onepage&q=advantage%20to%20use%20double%20haploid%20(DH)%20population%20for%20back%20crossing%20instead%20of%20the%20F1%20population%20to%20the%20recurrent%20parents&f=false

See here too..

https://books.google.co.in/books?id=mf8_AAAAQBAJ&pg=PA85&lpg=PA85&dq=advantage+to+use+double+haploid+(DH)+population+for+back+crossing+instead+of+the+F1+population+to+the+recurrent+parents&source=bl&ots=PCf1PmvXid&sig=tQ7pFYFYuw4kod11vINKx8HHOiI&hl=en&sa=X&ved=0ahUKEwip7eGvnujTAhVBv48KHW4LCNMQ6AEIMjAE#v=onepage&q=advantage%20to%20use%20double%20haploid%20(DH)%20population%20for%20back%20crossing%20instead%20of%20the%20F1%20population%20to%20the%20recurrent%20parents&f=false

More on topic..

http://www.biotecharticles.com/PDF_Articles/BA_3892_Mapping_Populations.pdf

See this too..

http://www.isbreeding.net/common/UploadFiles/file/publications/47_english.pdf

Explore this too..

https://books.google.co.in/books?id=b7z_DAAAQBAJ&pg=PT149&lpg=PT149&dq=advantage+to+use+double+haploid+(DH)+population+for+back+crossing+instead+of+the+F1+population+to+the+recurrent+parents&source=bl&ots=C1Ee17QoN6&sig=sEQQzUfJg12AreekSpndlHLo8Y4&hl=en&sa=X&ved=0ahUKEwip7eGvnujTAhVBv48KHW4LCNMQ6AEIQjAH#v=onepage&q=advantage%20to%20use%20double%20haploid%20(DH)%20population%20for%20back%20crossing%20instead%20of%20the%20F1%20population%20to%20the%20recurrent%20parents&f=false

thanks Surender Singh sb,  for providing nice and valueble information

use of double haploids population is the shortest way to produce fully homozyguous population for the whole genome of certain plant species which is more useful in genetic mapping compared to the continuous selfing required in case of development of RILs populations that usually used for genetic mapping