Study of Forage Characterization of Barley (Hordeum vulgare L.) Intercropped with Grass Pea (Lathyrus sativus L.), Forage Peas (Pisum avestum L.), Vetch (Vicia villosa L.) and Common Vetch (Vicia paninica L.) Affected by Plant Density under Rainfed Condit

Cereals and legumes are considered as important forage crops, because of their nutritional value, especially protein content in legumes and crude fiber in cereals. Intercropping may be a useful strategy to grow crops simultaneously, offering to improve resource utilization such as solar radiation, nutrients and water during growth and development. This is also an important method for sustainable crop production, particularly when inputs are limited. Higher yields have been documented for intercropping of beans and maize, barley and peas, oats and vetches wheat and peas, and wheat and beans. Using time and space, in addition, improving plant production methods in terms of environmental and human health, intercropping can increase agricultural production. In order to increasing soil fertility and improving plant growth and quality, in medicinal plants cultivation, elimination or reduction of chemical fertilizers, is very important. In terms of competition, this means that the components are not competing for the same ecological niches and then the interspecific competition is weaker than the intraspecific competition for a given factor. Intercrops can be more effective than sole crops in preempting resources used by weeds and suppressing weed growth, because complementary patterns of resource use and facilitative interactions between intercrop components can lead to a greater capture of light, water, and nutrients. Several indices such as land equivalent ratio (LER), time equivalent ratio (ATER), and relative value total (RVT), land utilization efficiency (LUE), relative crowding coefficient (K), and aggressivity (A) are used to describe the competition and the economic advantage of intercropped plants. In order to study the effect of plant density and intercropping ratio of annual forage legumes includes: grass pea (Lathyrus sativus L.), field pea (Pisum avestum L.), hairy vetch (Vicia villosa L.) and hungarian vetch (Vicia pannonica L.) on quantitative and qualitative barley performance in a randomized complete block design with three replications were conducted in Kurdistan Agricultural Research (Sanandaj) stations under rainfed condition during 2013 growing season. The treatments included five levels of legume seed densities (100, 150, 200, 250, 300 plant.m-2) and four seeding ratios (100% legume, 75% legume + 25% barley, 50% legume + 50% barley and 100% barley).In this experiment, fresh forage yield, dry matter, crude protein yield and land equivalent ratio (LER) were recorded. The crops were managed according to organic farming practices without pesticide or fertilizer use. No mechanical weeding was performed after sowing. Combined analysis of variance was performed using SAS version 9.1 (SAS Institute Inc., Cary, NC, USA) (SAS Institute Inc. 1988). Means of the treatments were compared, using Generalized Linear Model (GLM) method and the least significant difference (LSD) test at the 5% probability level. The data showed normal distribution and no transformation was required. Results showed that the highest and lowest fresh forage yield and dry matter yield were obtained from pure barley and pure legumes in 100 plant.m2 seed density, respectively. Intercropping ratio of 75% field pea+ 25% barley at 250 plant.m-2 density and 50% hairy vetch+ 50% barley at 300 plant.m-2 density with 0.94 and 0.86 t.ha-1 produced maximum crude protein yields, respectively. Intercropping ratio of 75% grass pea+25% barley at 300 plant/m-2 density, 75% field pea+ 25% barley at 200 plant.m-2 density, 50% hairy vetch+ 50% barley at 300 plant.m-2 density and 50% hungarian vetch+ 50% barley at 200 plant.m-2 density, with 1.19, 1.26, 1.16 and 1.13 LER values, respectively, performed the best efficiency in resources utilization in intercropping system. Based on these results, it can be concluded that intercropping of annual forage legumes includes: grass pea, field pea, hairy vetch and hungarian vetch with barley is a way for increasing productivity per unit area.