The Effect of Intercropping Patterns on Peppermint (Mentha piperita L.) Dry Biomass Yield and Essential Oil Content and Faba Bean (Vicia faba L.) Seed Yield

In order to evaluate the effect of peppermint and faba bean intercropping patterns, a field experiment was carried out as a randomized complete blocks design (RCBD) with 9 treatments and 3 replications at the Faculty of Agriculture, University of Maragheh, Iran during 2015 growing season. Treatments included sole planting of peppermint and faba bean and intercropping patterns with ratios of 1:1, 1:2, 2:1, 2:3, 3:2, 1:3 and 3:1 (peppermint: faba bean). The highest number of pods per plant (5.4), seeds per pod (3.7) and 100-seed weight (118.4 g) were achieved in the ratio of 2:3. The highest seed yield of faba bean per occupied unit of land when the latter species were planted with the ratios of 2:3 (268.3 g m-2) and 1:3 (250 g m-2). The highest seed yield of faba bean per intercropped unit of land area was related to faba bean sole cropped (189.8 g m-2) and 1:3 (187.5 g m-2) cropping pattern. Also, the highest dry mass yield of peppermint per occupied unit of land area was obtained in the 2:3 treatment (629 g m-2) with no significant difference with 3:2 and 1:3 treatments. The highest dry mass yield of peppermint per intercropped unit land area was observed in the peppermint sole cropped (320 g m-2) and ratio of 3:2 (303 g m-2) with no significant difference with 2:1, 2:3 and 3:1 cropping patterns. The highest peppermint essential oil percentage (2.15%) and essential oil yield (5.61 g m-2) were related to 2:3 and 3:2 treatments. In all cropping patterns (except of 1:1 treatment), the LER value was higher than 1, while LERs value was higher than 1 in 2:3, 3:2 and 1:3 treatments. The greatest value of LERs (1.31) was achieved in 2:3 cropping pattern. In conclusion, based on faba bean seed yield, peppermint essential oil content and yield and LERs, the ratio of 2:3 for peppermint:faba bean was superior to other treatments.