On the National Commodity and Derivatives Exchange, October contracts increased by Rs 35 to Rs 3,474 a quintal with an open interest of 1,25,890 lots.
November contracts gained by Rs 41 at Rs 3,579, with an open interest of 44,910 lots.
On the Rajkot Commodity Exchange, December contracts increased by Rs 44 to Rs 3,714. RCX spot castor declined by Rs 37.50 to Rs 3,410 a quintal.
Castor oil traded flat at Rs 720 for 10 kg.
Spot prices, however, decreased as recent rains have raised hopes of higher sowing of the crop that is grown during the rabi season.