Determination of drought stress tolerance of maize (Zea mays L.) and wheat (Triticum aestivum L.) with biochemical and physiological parameters

Drought is an important abiotic factor that limits the agricultural productivity and nowadays global warming increases the severity of the situation. It has been showed that water deficiency of soil has many effects on plant growth and development, photosynthesis, osmotic regulation and endogenous defense systems. Reactive oxygen species that occur due to drought cause oxidative reactions in cellular components and membrane damage. The aim of this study was to determine the tolerance of some maize and wheat (Triticum aestivum L.) cultivars which are the most important cereals that grown in our country and the world by physiological and biochemical analyses. With this purpose, wheat (Gelibolu, Aldane) and maize (Sakarya, Ada-9516) cultivars grown in perlite medium at optimum conditions (at 25℃, 250 µmol m-2s-1 light intensity, 16 hour light/8 hour dark, %40-50 humudity) for one week with half strength Hoagland solution were exposed to drought for 5 days by different concentrations (kontrol, -0.4 MPa and -0.8 MPa) of PEG 6000 solutions. At the end of the 12th day, some growth parameters (shoot length, leaf number, fresh and dry weight), relative water content, ion leakage, H2O2 level and some pigment (anthocyanin and flavonoid) contents were determined in harvested cultivars. Drought treatments affected adversely the growth parameters and relative water contents of wheat and maize cultivars. The elevated ratio of ion leakage of wheat and maize cultivars is an indicator of membrane damage and the increased level of H2O2 is an indicator of oxidative stress. The anthocyanin and flavonoid contents of all cultivars leaves were increased due to rising drought intensity. However, they could not able to prevent oxidative damage in the cultivars that were more sensitive (Gelibolu and Ada-9516). Drought damage increased with the elevated drought stress. The results of this study showed that wheat cultivar Aldane and maize cultivar Sakarya were more tolerant to the different severity of drought that exposed to both wheat and maize cultivars than the others.