Improving Quantitative and Qualitative Yield of Black Cumin (Nigella sativa L.) in Intercropping with Fenugreek (Trigonella foenum-graecum L.)

Intercropping system is one of the most important strategies for achieving sustainable agriculture goals. Intercropping increases biodiversity in agroecosystems and enhances yield on a given piece of land by making more efficient use of the available resources. In these systems, legumes are a key functional group, and are highly valued for the agroecological services they provide. Adding legumes in fields is justified by their natural ability to exploit atmospheric nitrogen. This additional source of N is expected to avoid inter-specific competition between plants and legumes for N acquisition. Medicinal plants play pivotal role in human health. The use of sustainable agriculture is the foundation for safe and healthy Medicinal plants. Therefore, the purpose of this research was evaluation of quantitative and qualitative traits of black cumin (Nigella sativa L.) and fenugreek (Trigonella foenum-greacum L.) in additive and replacement series of intercropping.

Field experiment was conducted at the Agricultural Research station, University of Kurdistan, during 2015 growing season. In this research, qualitative and quantitative traits of black cumin and fenugreek were investigated. Experimental design was randomized complete block with three replications. Experimental factors were 50% fenugreek + 50% black cumin, 25% black cumin + 75% fenugreek, 75% black cumin + 25% fenugreek, 100% black cumin + 12.5% fenugreek, 100% black cumin + 25% fenugreek, 100% black cumin + 37.5% fenugreek, 100% black cumin + 50% fenugreek based on replacement and additive series and their monocultures. The seeds were sown directly on 4th of May for both plants. In this study, morphological characteristics consisted of branch number per plant, follicle number per plant, seed number per follicle, 1000 seed weight, essential oil content, essential oil yield of black cumin and branch number per plant, pod number per plant, seed number per pod, 1000 seed weight of fenugreek and biological and seed yield were measured in both plants. Intercropping indexes included of LER and ATER were also evaluated. The obtained data were subjected to analysis of variance (ANOVA) using SAS statistical software and means were compared using the least significant difference test (L.S.D) at level of 0.05.

The results revealed that different intercropping ratios had significant effect on morphological traits, biological and seed yield of both plants. The usage of 100% black cumin + 12.5% fenugreek gave the highest values of branch number per plant (18.87), follicle Number per plant (29.73), Seed number per follicle (52.6), 1000-seed weight (2.67 g), seed yield (972.1 kg.ha-1), biological yield (2757.1 kg.ha-1) and essential oil yield (11.19 kg.ha-1) of black cumin. It seems that black cumin was more efficient for uptake nutrient resources in comparison with fenugreek. With increasing fenugreek density different traits of black cumin decreased in the other additive treatments. This decrement maybe related to the effect of density which increases competition. Statistical analysis revealed that all traits of fenugreek such as branch number per plant, pod number per plant, Seed number per pod, 1000-seed weight, biological yield and seed yield were 12.27, 16.80, 11.63, 15.77g, 3266.7 kg.ha-1 and 874.4 kg.ha-1, respectively. These values belonged to monoculture of fenugreek. Intercropping indexes included of LER (1.36) and ATER (1.30) showed higher values in 100% black cumin + 12.5% fenugreek treatment.

The highest values of most characteristics of black cumin were obtained from 100% black cumin + 12.5% fenugreek. Furthermore, it could be concluded that the mentioned additive series was the best treatment of intercropping and gave the highest LER and ATER due to improved growth condition.