Investigation of Forage Yield and Nutrients Uptake in Intercropping of Barley (Hordeum vulgare L.) and Grass Pea (Lathyrus sativus L.) Affected by Symbiosis with Glomus intraradices Fungus

Introduction Intercropping systems are one of the sustainable agricultural systems that defined as growing two or more plants simultaneously, lead to the use of more resources efficiently of nutrient water and land, improving plant productionIntercropping, as a new green revolution, is a sustainable strategy for the development of food production due to the lesser reliance of chemical fertilizer inputs compared with monocultures. In intercropping systems, plant nutrient uptake could improve the physical, chemical, and biological soil properties and higher nutrient mobilization in the rhizosphere. Arbuscular mycorrhizal fungi (AM) are preferred biofertilizers over other myriads of microorganisms that inhabit the interface between plant and soil. They are ubiquitous soil inhabitants and form the largest group which is predominantly associated with crops. Arbuscular mycorrhizal fungi can considerably improve plant growth, nutrients uptake, and transport, especially phosphorus, water status, and chlorophyll content. Previously studies demonstrated that higher productivity with AM fungi's application was attributed to higher nutrients availability such as P, K, Ca, Mg, etc. Thus, an experiment was conducted to evaluate the effects of barley's different intercropping patterns with grass pea and symbiosis with AM fungus on the forage yield and nutrients absorption, including N, P, K, Fe, Zn, Mn, Ca, and Mg.   Materials and Methods In order to investigate the forage nutrients content and in intercropping of barley (Hordeum vulgare L.) with grass pea (Lathyrus sativus L.) under application of arbuscular mycorrhizal fungi, a field experiment was performed as a factorial layout based on randomized complete block design (RCBD) with ten treatments and three replications at the faculty of Agriculture, University of Maragheh, Iran, during 2017. The first factor included different planting patterns (monoculture of barley, monoculture of grass pea, 75% grass pea+ 25% barley, 50% grass pea+ 50% barley, 25% grass pea+ 75% barley), and the second factor was inoculated and non-inoculated with Glomus intraradices fungus. All data were statistically analyzed using analysis of variance (ANOVA) using MSTAT-C statistical software. The Duncan's multiple range test was used to compare means at a 5% probability level.   Results and Discussion This study demonstrated that the macro and micronutrient content were significantly affected by different cropping patterns with the application of AM fungi. The greatest barley forage yield belonged to inoculated barley monoculture. Furthermore, the results demonstrated that the inoculated barley forage yield in monoculture was 47.48% more than the non-inoculated. The highest grass pea forage yield was achieved in monocultures and followed by a ratio of 75% grass pea+ 25% barley symbiosis with mycorrhizae fungus. Also, the highest nutrient content was achieved in grass pea monoculture with the application of AM fungi. Between different intercropping patterns, the highest nutrients content was obtained in the 75% grass pea+ 25% barley with the application of AM fungus. The higher nutrients uptake was attributed to increasing the absorption surface and improving nutrients availability with the application of AM fungi. Also, Varma et al. (2018) reported that the application of AM fungi in intercropping systems increased the transfer of the nutrients, especially nitrogen, to component plants that resulted in higher nutrients uptake in plants. These authors also reported that the higher nitrogen content with the application of AM fungi attributed to the higher activity of nitrate reductase and dikinase glucan enzymes that resulted in higher nitrogen availability for plants.   Conclusion According to the results of this research, intercropping treatments of barley/grass pea with Glomus intraradices considerably influenced by the absorption of nutrients and forage yield. The content of concentration nitrogen, phosphorus, potassium iron, zinc, manganese, magnesium, and calcium were highest at all intercropping patterns coincided with the application of mycorrhiza fungi than the non-inoculated monoculture of barley. Also, between different intercropping patterns, the highest nutrients content was obtained in 75% grass pea+ 25% barley pattern accompanied by application of mycorrhiza that suggested as a better pattern to achievement high-quality forage for farmers. Therefore, intercropping of barley/grass pea with the application of mycorrhizae can improve forage quality of barley and grass pea from the point of view concentration of nutrients and were influential in production forage with high quantity.