Competition indices of intercropping of hyssop (Hyssopus officinalis L.) and fenugreek (Trigonella foenum-graecum L.) in different soil moisture conditions

The field experiment was carried out as spilt plot experiment with four replications based on a randomized complete block design at the University of Shahrekord's research farm in 2017-2018 to investigate the competitive indices and yield of two medicinal plant species, namely hyssop and fenugreek. The main plot has two soil moisture levels, with irrigation after drainage at 25 and 50% of field capacity. The sub-plot had five levels of planting pattern, including 100% hyssop, 100% fenugreek, hyssop 50%: fenugreek 50%, hyssop 75%: fenugreek 25%, and hyssop 25%: fenugreek 75% based on replacement series. The results showed that under drought stress, the land equivalent ratio (LER) of hyssop intercropped with fenugreek was higher than mono-cropping, with a significant difference (p£0.01). In this study, intercropping hyssop (50%) with fenugreek (50%) under mild stress increased the LER by 25.6% when compared to mono-cropping. When compared to mono-cropping, the average total relative density (K) increased in all intercropping ratios, and the total actual yield loss (ALYt) was positive in all intercropping ratios, indicating the usefulness of intercropping the two plants. Overall, the highest value of the system productivity index (SPI) was obtained in the intercropping hyssop (75%) with fenugreek (25%). Finally, intercropping hyssop with fenugreek can increase the productivity of a hyssop cultivation system.