Root System of Different Barley Cultivars Influenced by Applications of Different Fertilizer Sources under Dryland Farming

Biofertilizers play a crucial role in soil fertility by dissolving stabilized phosphates and producing the nutrients needed for plant growth in the soil. One of the most important soil microorganisms is mycorrhizal fungi. Mycorrhizal fungi, with their extensive hyphae network and increasing the level and speed of root uptake, increases the plant efficiency in nutrients, especially inactive elements such as phosphorus, and improves plant growth. Mycorrhiza fungi increase nutrient uptake of plants due to stimulation of root formation and subsequent increase in root level through the production of auxin and gibberellin hormones. By extending the root system, mycorrhizal fungi increase the total absorption surface of inoculated plants and thus improves crop plant access to water absorption. Considering the important and critical role of roots in crops, having sufficient information and understanding the morphological characteristics of the root system is important. Therefore, this study was conducted to investigate the role of the root system in the presence of mycorrhizal fungi in new barley cultivars in the Ilam region in rainfed conditions. In order to investigate the effect of inoculation with mycorrhiza fungi on the root system of barley cultivars in rainfed conditions, a factorial field experiment was carried out based on a randomized complete block design with three replications in the farm station of Sarablah Agricultural Research Center during 2019-2020 cropping season. Experimental treatments were including barley cultivars (Mahali, Mahour, Khorram, and Fardan) and fertilizer sources treatment including control (without fertilizer), 50% P fertilizer, mycorrhizal fungi (Glomus mosseae, Glomus etunicatum, and Rhizophagus irregularis), mycorrhizal fungi+50% P chemical fertilizer and 100% P chemical fertilizer. Root-related characteristics were measured inside the field at the pollination stage using a metal cylinder with dimensions of 30 cm in length and 2 cm in width, which had been pre-designed by hand. To measure grain yield after removing the marginal effects (50 cm from the beginning and end) were recorded for each plot. Statistical analysis of the data of this research project was done by SAS software, means were compared by Duncan’s multiple range test method, and graphs were prepared by Excel software This study showed that the interaction between cultivar× fertilizer sources was significant on the characteristics of rainfed barley roots. So that the maximum root length (76.6%), root volume (75.7%), root area (73.3%), root length density (76.8%), root tissue density (89.9%), root-specific mass (65.7%), and root surface area density (70.6%) was obtained from Fardan cultivar×mycorrhizal fungi+50% P chemical fertilizer compared to control treatment (without fertilizer source). It seems that the presence of mycorrhizal fungi has caused changes in root morphology so that the spread of mycorrhizal mycelium related to the internal tissues of the root has increased root length.  The results of this study showed that the use of mycorrhizal fungi increased root system and root morphological changes in new barley cultivars. What is clear and has been mentioned in the reports of other researchers is that the mycorrhizal fungi can gain maximum use of moisture and nutrient uptake by creating a strong rooting system in the host plant from the rhizosphere. Recent research has shown that Fardan cultivar in the presence of mycorrhiza fungi had maximum root length, root volume, root area, root length density, root tissue density, and finally, root surface area density, and when no fertilizer source was used, a large reduction in the rooting system was observed in all cultivars. Therefore, among the cultivars used, Fardan cultivar with co-consumption of mycorrhizal fungi and 50% of P fertilizer can cause the development of root system and ultimately increase grain yield in the region under dryland conditions.