Soya (Glycine Max L.) Genotiplerinde Su Taşkınının İndüklediği Morfolojik, Fizyolojik ve Biyokimyasal Değişimler

Abstract

Changes in the precipitation regime and the increase in the frequency of extremes (drought and flooding) due to global warming negatively affect plant growth and development. Within the scope of this thesis, it was aimed to investigate the morphological, physiological and biochemical changes in two soybean (Glycine max (L.)Merr.) genotypes with different tolerance degree induced by two different types of flooding, partial submergence and complete submergence. The seeds of soybean genotypes were germinated in a controlled growth cabinet at 25±1°C temperature, 16 hours light/8 hours dark photoperiod, 200 µmol m-2s-1 light intensity and 45-55% humidity conditions for 7 days. At the end of seven days, the seedlings were transferred to pots (2 individuals in each pot) containing 150 g of silica sand (aquarium sand), watered with ½ diluted Hoagland nutrient solution and grown for 3 days in a controlled growth cabinet. Afterwards, the 10-day-old seedlings were exposed to partial submerge and complete submerged for 4 days. At the end of fourteen days, the seedlings were harvested for various morphological, physiological and biochemical analyzes. Hypoxia (oxygen deficiency) conditions caused by flooding led to significant decrease in shoot and root lengths, biomass, relative water content and leaf area of soybean genotypes (Cinsoy and Traksoy). Complete submerged flooding affected the photosynthetic activity of both genotypes more negatively than partial submerged flooding. Flooding led to the changes in fluorescence transients (Kaustky curve), decreases in specific ABS/RC, TRO/RC, ETO/RC, DIO/RC, RE/RC) and phenomenological energy fluxes (ABS/CS, TRO/CSO, ETO/CSO, DIO/CSO) in the thylakoid membranes of genotypes. These changes in JIP-test parameters caused decreases in the performance indexes (PIABS / PITOP) of the genotypes. The decrease in photosynthetic activity caused by flooding is probably due to disruption of the membrane structure, increase in inactive reaction centers and thus the inability to direct the excitation energy to photochemistry. Flooding caused membrane damages and increase in production of reactive oxygen species in cells of soybean genotypes. MDA and H2O2 contents of genotypes support this hypothesis. Reactive oxygen species have been tried to be detoxified by enzymatic (SOD, GR, APX and POD) and non-enzymatic antioxidants (anthocyanin and flavonoid) of soybean genotypes. In this context, the tolerant Cinsoy genotype exhibited performance more effectively and successfully than Traksoy genotype. With the outputs obtained within the scope of this thesis; Cinsoy genotype is recommended for cultivation in agricultural region that are prone to both partial submerged and complete submerged flooding.