Kalsiyum Uygulamasının Su Baskını Stresine Maruz Bırakılan Soya Bitkisinin (Glycine max L.) Gelişimi Üzerine Etkileri

Abstract

Due to climate change, flood stress has emerged as a significant abiotic factor that adversely affects plant development and agricultural productivity on a global scale. The frequency and severity of floods are increasing, which is also being experienced in our country, particularly in the Black Sea and Marmara regions, leading to agricultural yield losses. These regions, frequently affected by floods, are also areas where soybean cultivation, particularly non-flood-tolerant varieties, is conducted. Literature indicates that it is possible to enhance stress tolerance in plants subjected to stress through various treatments. Among these treatments, the use of different calcium salts has been shown to activate signaling pathways that confer stress resistance. In light of this information, this thesis investigates whether pre-treatments with 10 mM calcium, identified in preliminary trials, can enhance flood tolerance (submergence, partial submergence, and complete submergence) in the moderately flood-tolerant soybean genotype Cinsoy. This was assessed through morphological, physiological, and biochemical analyses including biomass, root-shoot length, relative water content (RWC), pigment contents (chlorophyll, carotenoid, anthocyanin, and flavonoid), membrane integrity, photochemical activity, and the activities of enzymes such as POD, GR, and APX. The results indicated that the 10 mM calcium treatment, considering the duration of application within the scope of this thesis, had a more pronounced effect on physiological and biochemical pathways (photosynthesis and antioxidant systems) rather than morphological effects. The Cinsoy genotype effectively increased POD enzyme activity to mitigate the harmful effects of reactive oxygen species (ROS), performing detoxification more successfully compared to other enzymes. Furthermore, increased H₂O₂ levels in plants subjected to flood stress may have acted as a signaling molecule and/or free radical, triggering POD activity and contributing to tolerance acquisition. This situation supports the protection of plants from oxidative damage and their adaptation to stress conditions.