The effects of intercropping and plant density on the growth and yield characteristics of quinoa and guar

Climate change has caused a decline in agricultural production and an increase in costs. To address this situation, intercropping is an agricultural practice that aims to maximize biomass. In order to assess the impact of intercropping and plant density on the growth and grain yield of Quinoa and Guar, two experiments were conducted during growing seasons of the 2019 and 2021. The experiments were conducted in Mashhad (in northeastern Iran) and Rudan (in southern Iran). The study employed a randomized complete block design and was carried out as a factorial experiment with three replications. The experimental factors included intercropping ratio (Q: sole quinoa, G: sole guar, and quinoa + guar in 1:1, 2:1, and 1:2 ratio) and plant density (10, 15, and 20 plants/m²). The highest mean quinoa grain yield (1114.92 kg/ha) was achieved in Mashhad in pure quinoa cultivation at 10 plants/m²; the lowest value (558.8 kg/ha) was recorded in Rudan in the 2quar:1quinoa treatment at 20 plants/m². When the interaction effects of intercropping and plant density were considered, the highest grain yield for guar (1934.08 kg/ha) was achieved in pure guar cultivation at 10 plants/m², and the lowest value (1181.24 kg/ha) was found in the 2guar:1quinoa treatment at 20 plants/m². The highest crude fiber content in guar grains was observed in the 1guar:1quinoa treatment at 10 plants/m². Our findings showed that the land equivalent ratio was significantly higher in the intercropping treatments. In total, intercropping resulted in an average of 54% higher yield compared to monoculture. The morphological differences between these 2 plants such as the difference in height, growth period, and ripening time could contribute to the increased overall productivity under intercropping. In conclusion, this study demonstrated that changing the ratios and densities of intercropped quinoa and guar, while taking into account morphological differences between the crops, led to significant yield differences in comparison to sole cropping.