Effect of Intercropping Ratios of Cumin (Cuminum cyminum L.) with Persian Shallot (Allium altissimum Regel.) on their Agronomic Criteria and Land Equivalent Ratio

Medicinal plants are a rich source of bioactive compounds, and these plants are thought to be safe to human beings and the environment compared to the synthetic medicines for the treatment of many diseases. The active principles of the plants are generally secondary metabolites. Cumin (Cuminum cyminum L.) is an herbaceous and annual medicinal plant belonging to Apiaceae family which is planted in arid and semi-arid regions of Iran. Persian shallot (Allium altissimum Regel.) is another medicinal, industrial and perennial plant that has underground bulbs. It is one of the most important Allium species in Iran, which normally grows in semi-cold to very cold highlands. In the last decade, agricultural production, which is mainly based on the application of chemical inputs, is causing environmental impacts. The use of ecological farming approaches, enhancing yield and quality, they will be effective. Intercropping allows for improved resource use efficiency such as light, water and nutrients and beneficial interactions between the companion plants. It works to decrease the spread of plant diseases by reducing the quantity of susceptible host plants. Other benefits of intercropping include optimal use of resources, stabilization of yield, weed control, improved soil fertility, and higher economic returns. This study has evaluated the effect of intercropping ratios as replacement series of cumin and Persian shallot on agronomic criteria such as yield components, yield, harvest index, dry matter accumulation and land equivalent ratio.

This experiment was conducted based on a randomized complete block design with three replications at the Agricultural Research Station, College of Agriculture, Ferdowsi University of Mashhad during growing season of 2014-2015. Intercropping ratios as replacement series such as 80% cumin+20% Persian shallot, 60% cumin+40% Persian shallot, 50% cumin+50% Persian shallot, 40% cumin+60% Persian shallot, 20% cumin+80% Persian shallot and their pure culture were considered as treatments. Plant density for Persian shallot bulbs and cumin seeds were considered as 10 bulbs.m-2 and 120 plants.m-2, respectively. Studied traits were umbel numbers per plant, seed numbers per umbel, 1000-seed weight, biological yield and seed yield of cumin and daughter bulb diameter, mother bulb diameter, fresh weight of daughter bulb, fresh weight of mother bulb, biological yield, fresh yield of bulb, dry weight of bulb of Persian shallot and land equivalent ratio (LER).The LER was computed through the following equation:Where, Yij: Yield of cumin under intercropping conditions, Yji: Yield of Persian shallot under intercropping conditions, Yii: Yield of cumin under sole crop conditions and Yjj: Yield of Persian shallot under sole crop conditions. The treatments were run as an analysis of variance (ANOVA) to determine if significant differences existed among means. Multiple comparison tests were conducted for significant effects using the LSD test.

The results showed that the effect of intercropping ratios was significant (p≤0.05) on yield and yield components of cumin and Persian shallot. By decreasing intercropping ratios of Persian shallot improved its criteria. Diameter of mother bulb and production of daughter bulb in intercropping ratios were increased up to 52 and 68% compared to sole culture, respectively. Studied traits of cumin were improved by changing in planting ratios from intercropping to its pure culture. The maximum amounts of dry bulb weight were related to pure culture (82.9 g.m-2) and 20% cumin+80% Persian shallot (85.3 g.m-2). The highest seed yield of cumin was observed in pure culture with 115 g.m-2. The highest and the lowest LER were computed in 50% cumin+50% Persian shallot (1.49) and 80% cumin+20% Persian shallot (1.15).

Intercropping of Persian shallot and cumin had significantly effect on their yield and yield components. The results confirmed the better use of resources especially for radiation and water of these plants in intercropping ratios. In general, it seems that intercropping may be suitable cropping approach for sustainable production of medicinal plants. Acknowledgement This research was funded by Vice Chancellor for Research of Ferdowsi University of Mashhad, which is hereby acknowledged.