Beer Hops

I did some research on trade growing hops. beer hops can be grown commercially in the tropics without problems? Where can I get more information about growing hops?

The latitude recommended for growing hops is 35-55 degrees in both northern and southern hemispheres, but the hops may be grown outside of this band. The vines will grow in the tropics, but apparently not produce cones necessary, or hops, used in the manufacture of beer. The main problem seems to be the length of day. Hops, the length of day more than they get in the tropics. Thus, you can direct your research in this area.
http://beeradvocate.com/forum/read/12459 ...
http://brewery.org/library/HopGrow.html