you also try cppu or cow urine for better retention of fruit set

The following links may be useful:

http://www.cabi.org/gara/FullTextPDF/Pre2000/19770349985.pdf

http://hortsci.ashspublications.org/content/45/6/887.full.pdf+html

http://cocos.sljol.info/articles/abstract/10.4038/cocos.v10i0.2138/

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwjFgbvhtuTTAhVEuo8KHS1FCb8QFgg7MAQ&url=http%3A%2F%2Fjnsfsl.sljol.info%2Farticles%2F10.4038%2Fjnsfsr.v43i3.7955%2Fgalley%2F6000%2Fdownload%2F&usg=AFQjCNFN3LOadgfclekD2-G54bVVgcgxjg

Kindly check

http://www.arccjournals.com/uploads/articles/asd293001.pdf

Check here also..

http://www.tandfonline.com/doi/pdf/10.1080/23311932.2015.1010415

Explore here too..

http://www.tandfonline.com/doi/full/10.1080/23311932.2015.1010415

See this too..

https://link.springer.com/article/10.1007/s11240-008-9473-y

See this also..

http://www.indianjournals.com/ijor.aspx?target=ijor:joh&volume=10&issue=1&article=008

Also to be explored..

http://www.actahort.org/books/78/78_35.htm

Explore this also..

https://link.springer.com/chapter/10.1007/978-3-642-74448-8_26#page-1

Thanks singhsir, nilaysir and pujarisir.

If you can add regarding foliar application of NAA in coconut, it will be highly helpful for me. 

Thanks again.

please check

http://shodhganga.inflibnet.ac.in/bitstream/10603/5187/6/06_chapter%202.pdf

https://www.ipipotash.org/udocs/5_Coconut-Green_Dwarf_Variety.pdf

http://www.arccjournals.com/uploads/articles/asd293001.pdf

Thanks Dr. Dhiasir.