These are called JAAPI is a traditional conical hat from Assam, India made from tightly woven bamboo and/or cane and tokou paat (Trachycarpus martianus) a large, palm leaf. So the farmers wear to protect themselves from sun rays and rain. So in the picture we can see the place is fully covered with clouds so they didn't wore JAAPI they kept it on the bunds . These clouds helped farmers to get rid of sun and burden of JAAPI on their head .