Study of the effect of irrigation, mycorrhiza, and azospirillum on the quantitative and qualitative yield of barley varieties

This field study was conducted with the objective of reducing or alleviating the drought stress effect on yield and yield components of barley varieties by applying biological fertilizers in two consecutive years within the framework of a split plot randomized complete block design with three replications. In the first year of the experiment, the main plot was irrigation at two levels (normal irrigation or full irrigation during the plant growth period, and irrigation until 50% of spike stage) and sub-plot was barley variety (Kavir, Valfajr, Nusrat, and Yusef). In the second year of the experiment, the first factor was irrigation at four levels (full irrigation during the plant growth as the control, irrigation until 50% of spike stage, irrigation until 50% of booting stage, and rainfed cultivation). The second factor was biological fertilizer application at four levels (Azospirillum lipoferum growth-stimulating bacterium, Mycorrhizal fungus Glomus intraradices, combination of Mycorrhizal and Azospirillium lipoform, and control). The third factor was barley variety at three levels (the superior and the susceptible varieties selected from the first year experiment and Abidar rainfed variety). In the normal irrigation conditions (non-stress), the maximum grain yield was 7775 kg/ha for the Kavir variety, and the minimum grain yield was 5650 kg/ha for the Valfajr variety. In irrigation stress conditions (irrigation up to 50% of spike stage), the maximum grain yield was 6209.4 kg/ha for the Nosrat variety, and the minimum grain yield was 4167.7 kg/ha for the Kavir variety. In this research, the Nosrat variety had the maximum tolerance against stress among the studied varieties. However, the Valfajr variety showed minimum drought stress tolerance. According to the results of the first year experiment, two Nosrat and Valfajr varieties were selected. The results of the second year experiment showed that applying Azospirillum lipoferum growth-stimulating bacterium, Mycorrhizal fungus, and the combination of Mycorrhizal and Azospirillium lipoform increased the grain yield up to 2.02, 2.38, and 3.31% compared to the control treatment, respectively. Full irrigation during the plant growth period compared to irrigation treatments up to 50% of the booting stage and rainfed cultivation increased the grain yield by 4.43% and 10.04%, respectively. In general, the Valfajr variety was selected due to the lower percentage of grain yield reduction compared to other varieties and the superiority of this variety in terms of stress sensitivity index, and this variety has the potential to become a suitable commercial variety.