Drought is one of the main limiting factors affecting the growth and productivity of plants. Drought stress affects plant growth in different ways through a series of anatomical, morphological, physiological and biochemical changes. Therefore, it is important to develop alternative methods to protect plants against drought stress. Turkey has one the most unique cultivated areas of different medicinal and aromatic plants including Calendula officinalis. Despite its considerable importance and use as a medicinal plant, its commercial production is very limited. In this study, the effects of different rhizobacteria and algal species treatments (B0: Control, B1; Azospirillum lipoferum, B2: Bacillus megaterium, B3: Chlorella saccharophila) on several physiological and biochemical parameters in C. officinalis were studied under irrigation regimes (normal irrigation (K1), 50% irrigation (K2) and 25% irrigation (K3). The results showed that the application of different rhizobacterial and algal species had positive effects by reducing the limited irrigation stress. Also, the range of different physiological and biochemical parameters values, including leaf relative water content (RWC), ion leakage in leaf tissues (ILLT), membrane endurance index (MEI), chlorophyll content, nitrogen balance index, MDA, total antioxidant activity, total phenolic content and total amount of flavonoids were determined as 61.8 - 77.2%, 29.2 - 42.8%, 57.2 - 68.9%, 26.8 - 38.2 µg / cm2, 110.6 - 158.0 mg / g, 0.276 - 573.0 nmol g-1, 19.92 – 55.92 Mmol TE/ g, 27.37 – 68.75 mg GAE/g and 9.49 – 17.88 mg QE / 100g, respectively. The results revealed that C. officinalis could be commercially cultivated as a drought-resistant plant species in arid and semi-arid regions of Turkey.

27.1.2022