Determination of the effects of PGPR isolates and algae on plant growth in broad bean (Vicia faba L.) grown under water stress conditions

In regions exposed to drought stress, the use of bacteria applications to promote yield and quality has increased. This study was carried out to determine the effects of rhizobacteria and algae treatments on some biochemical and physiological properties of broad bean (Vicia faba L.) grown under water stress conditions. According to the completely randomized experimental design, the study was carried out in 4 replications in factorial order. In the experiment, the Filiz-99 broad bean variety was used as a plant material. In the study, 4 different biological applications (control, blue-green algae, and 2 different bacteria) and 3 different irrigation levels – 100% (NI), 50% (RI1), and 25% (RI2) – have been applied. In the study, properties such as root and stem length, stem and root fresh weight, stem, and root dry weight, nitrogen balance index, antioxidant, flavonoid, and phenolic properties were examined. Root length changed between 21.37–25.62 cm in bacteria and algae applications, and the highest value was obtained from the B1 application with 25.62 g. At increasing water stress levels, the nitrogen balance index varied in the range of 128.01–77.50%. In bacteria and algae applications, the highest value was obtained from the B1 application. While the phenolic content ranged between 127.53 and 134.31 mg GAE (Gallic Acid Equivalents) g–1 with increasing water stress, the highest value among biological applications was B1 application with 138.06 mg GAE g–1. As a result of the interaction of factors, the highest phenolic values were obtained from B1 × RI2 (149.85 mg GAE g–1), B2 × RI2 (137.05 mg GAE g–1), B0 × NI (127.43 mg GAE g–1), and B0 × RI2 (123.69 mg GAE g–1) applications, while the lowest values were obtained from B2 × NI (123.22 mg GAE g–1), Alg × RI2 (126.65 mg GAE g–1), Alg × NI (127.75 mg GAE g–1), and B1 × NI (131.73 mg GAE g–1) applications. In the study, it was determined that bacterial applications were more effective than algae applications.