Effect of population density and spatial arrangements on the productivity of Zea mays L. and Mentha spicata L. in intercropping systems at wondo genet, rift valley of Ethiopia


D. Abayechaw*, W. Worku and T. Ayalew

In Ethiopia, intercropping of medicinal and aromatic plants, like spearmint, with cereals is not well known and undertaken as a common practice. Intercropping spearmint (Sm) with major produced cereal crops such as maize (Mz) can give a chance for farmers to diversify their incomes. Therefore, the field experiment was conducted at Wondo Genet, Rift Valley of Ethiopia under rain-fed conditions during the 2020 cropping season to investigate the effect of spearmint population density and spatial arrangements on the productivity of the maize-spearmint intercropping. The experiment was laid out in a factorial arrangement based on a randomized complete block design with three replications. Treatments were made from a factorial combination of spearmint population density (100, 75, 50, and 25%), and spatial arrangements (1Mz:1Sm, and 1Mz:2Sm) ratio. Data on phenological, growth and yield-related crop parameters were collected following their respective standard methods and procedures and further subjected to analysis of variance (ANOVA) using SAS version 9.4. Whenever the ANOVA result showed a significant difference among treatments for a parameter mean separation was further done using the least significant difference (LSD). The analysis of variance showed that the main effect, their interaction, and cropping system didn’t significant effect (P>0.05) on phenological, vegetative growth, and yield-related parameters of the main crop, maize. On the other hand, the spatial arrangement by population density interaction significantly affected the total fresh above ground-biomass, and leaf yield, and essential oil yield of spearmint where the maximum (22.70-ton, 12.72-ton, and 0.047-ton ha-1) in their respective order were recorded at 100% spearmint population density with a double row arrangement respectively. The sole spearmint was superior to other intercropped treatments in each of the two-harvesting cycles for above-ground biomass, leaf, and essential oil yield. The LER values indicated that intercropping maize with a 100% spearmint population at the double row arrangement gave a 63% intercropping advantage with a monetary advantage index (MAI) of 71108 ETB followed by a 75% spearmint population at the same density with 58% advantage and MAI of 65275 ETB. Therefore, intercropping of 75% spearmint population density at double row arrangement with maize could be recommended for the study area.

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