i searched on the net not much info i got. finally i decided to do an experiment. I found an interesting answer. i took unpolished rice grains (5 Nos), 5 grains of the same variety with husk, similarly another variety of paddy (5 grains without husk and 5 with husk) and put them in a petri-plate with wet tissue papers for germination. Interestingly, in less than 22 hrs, the slender grains without husk germinated and with husk, yet to germinate. pic is attached herewith.