Prices of mustard seed were up in Jaipur due to a fall in arrivals along with improved demand from domestic oil millers and crushers. Expectations of a fall in output of the oilseed in Rajasthan further supported prices. Production of mustard in Rajasthan, a key grower of the commodity, is seen falling 16% on year to 3.2 mln tn, according to the second advance estimates.