In order to assess the factors responsible for yield decline in Iorio (Brassica rapa  syn.  Brassica campestris var. toria), field survey was carried out at Bardiya and Dang in 1999 and Chitwan and Bora in 2000 and field trials were conducted at National Oilseed Research Program (NORP), Nawalpur Sarlahi during 1997/98-199912000. Seed yield decline in toria has been realized and felt throughout the torin growing areas of the kingdom. Low or no use of fertilizer and manures, declining inherent soil fertility, non-adoption of plant protection measures, use of local cultivars, lack of irrigation facility and weeds were identified as the major factors responsible for toria yield decline at farmers' field. Pollinators (honey bees) and chemical fertilizers (NPK) were the two main constraints responsible for toria yield decline at National Oilseed Research Program  Nawalpur, Sarlahi, which reduced the seed yield by 46.53% and 29.48% respectively. Full package of practice increased the toria seed yield and net return by 95.48 and 27%, respectively compared to farmer’s practices. Honeybees were helpful in seed setting and oil production in toria.

In order to assess the factors responsible for yield decline in Iorio (Brassica rapa  syn.  Brassica campestris var. toria), field survey was carried out at Bardiya and Dang in 1999 and Chitwan and Bora in 2000 and field trials were conducted at National Oilseed Research Program (NORP), Nawalpur Sarlahi during 1997/98-199912000. Seed yield decline in toria has been realized and felt throughout the torin growing areas of the kingdom. Low or no use of fertilizer and manures, declining inherent soil fertility, non-adoption of plant protection measures, use of local cultivars, lack of irrigation facility and weeds were identified as the major factors responsible for toria yield decline at farmers' field. Pollinators (honey bees) and chemical fertilizers (NPK) were the two main constraints responsible for toria yield decline at National Oilseed Research Program  Nawalpur, Sarlahi, which reduced the seed yield by 46.53% and 29.48% respectively. Full package of practice increased the toria seed yield and net return by 95.48 and 27%, respectively compared to farmer’s practices. Honeybees were helpful in seed setting and oil production in toria.