Effect of soybean and sesame intercropping on grain yield and yield components under the low-nitrogen condition

A field experiment was carried out as a randomized complete block design with four replications to investigate the agronomic traits and grain yields of sesame and soybean intercropping at Research Farm of Sari Agricultural Science and Natural Resources University for two years (2018-2019). The mixing ratios were 25:75, 50:50, 75:25 (soybean: sesame, respectively), and monoculture of two crops. Results showed sesame monoculture had the highest branches and capsules per plant. In the Soybean crop, the mixing ratio of 50:50 was more successful in producing the branches and pods per plant than other mixing ratios. Also, sesame and soybean monocultures had the highest grain yield with an average of 2077.43 and 4365.32 kg. ha-1, respectively,. The mixing ratio of 50:50 and 75:25 (1.17 and 1.01 in average, respectively) had higher LER than one. Finally, the more significant contribution of complementary effect (83.98 %) and selective effect (76.73 %) on grain yield at 50:50 and 75:25 mixing ratio increased the productivity of the intercropping system, respectively.  Meanwhile, the little increase in efficiency in the 75:25 mixing ratio was related to the 76.73% contribution of the selective effect and the competitive dominance of soybeans in the intercropping.