Effects of planting density and variety on productivity of maize-faba bean intercropping system

Maize (Zea mays)-faba bean (Vicia faba) intercropping is a recent practice in eastern Ethiopia and there is limited information on optimum planting density and suitable varieties of faba bean for productive intercropping with maize. Therefore, a field experiment was conducted in eastern Ethiopia during the 2018 and 2019 main cropping seasons to determine the effects of variety and density of faba bean on the yield components of the crops and the productivity of the intercropping. Treatments consisted of three farmers' varieties (Yeferenji Baqela, Yehabesha Baqela, Batte) and one improved variety (Gachena)intercropped with maize in an additive design at three plant densities (25%, 50%, and 75% of their recommended sole crop density of 250,000 plants ha^-1) and the recommended 100% plant density of sole faba bean and sole maize. A randomized complete block design in a factorial arrangement of treatments replicated three times per treatment was used. Analysis of data revealed that sole maize produced a significantly higher number of ears per plant (1.70), thousand kernel weight (287.9 g), aboveground dry biomass (19.11 t ha^-1) and grain yield (6.16 t ha^-1) than intercropped maize. Among the intercropping systems, maize intercropped with 25% of the sole faba bean produced a significantly higher grain yield (5.56 t ha^-1) than 50% and 75% plant density. Similarly, the 75% plant density of the sole faba bean intercropped with maize produced the highest grain yield (0.96 t ha^-1) compared to the 25% and 50% plant densities. Faba bean planted in the sole system produced a significantly higher seed yield (2.08 t ha^-1) than the intercropped faba bean with maize. Faba bean variety Gachena was found to be superior than the other varieties in number of pods per plant (10.23), aboveground dry biomass (3.73 t ha^-1), grain yield (1.96 t ha^-1) and harvest index (26.75%). Land equivalent ratio showed 18.4% higher yield advantage when maize was intercropped with faba bean than when it was sole-cropped. The highest gross monetary value (99318 Ethiopian Birr ha^-1) and maize equivalent yield (6621.2 kg ha^-1) were obtained from maize intercropped with Gachena faba bean variety with no significant differences among the plant densities. It is concluded that intercropping of maize with 75% plant density of improved Gachena variety resulted in superior performance of the system in terms of productivity and economic return.