Improving essential oil yield and compositions of basil (Ocimum basilicum L.) through mycorrhiza fungi and bacteria in intercropping system

A two-year study was conducted to investigate the effects of fertilizer treatments on growth characteristics, essential oil (EO) yield and compositions of basil ( Ocimum basilicum L.) in intercropping with fenugreek ( Trigonella foenum - graecum L.). A factorial experiment was arranged in a randomized complete block design with three replicates in 2021 and 2022. The first factor was cropping pattern including sole cropping of basil and fenugreek, strip intercropping of basil (B)-fenugreek (F) with replacement method in the ratios of 2B:2F, 4B:2F, 5B:3F and an additive intercropping of 100% basil + 50% of fenugreek (100B:50F). The second factor was fertilizer at three levels including application of 100% chemical fertilizer (100% CF), 50% chemical fertilizer + biofertilizer (50% CF + Bio) and biofertilizer (Bio). The greatest basil height was observed in 2B:2F cropping pattern and 50% CF + Bio treatment (50.39 cm). The greatest yield of dry herbage was observed in 5B:3B cropping pattern with 100% CF and 50% CF + Bio treatments. The greatest yields of EO were observed in sole basil and 2B:2F intercropping (0.87 g m ^− 2 ), in 50% CF + Bio treatment. Methyl chavicol, methyl eugenol, β-caryophyllene and 1,8-cineole, were the main chemical constitutes of EO. The contents of major components of EO were affected differently by cropping pattern and fertilizer. The greatest content of methyl chavicol (53.7%), was observed in 2B:2F and Bio fertilizer treatment. At all treatments, the land equivalence ratios (LER) were more than 1.0 and the highest value (1.99) was obtained in 2B:2F intercropping with 50% CF + Bio treatment. Application of 50% CF + Bio fertilizer treatment in 2B:2F intercropping, improved the productivity of basil-fenugreek intercropping, enhanced the EO compositions and could be used in sustainable production of basil.