Fikret Yasar

Determination of anti-oxidant activities in some melon (Cucumis melo L.) varieties and cultivars under salt stress

Summary The response of the antioxidant system to salt stress was studied in leaves of seedlings of four Turkish melon (Cucumis melo L.) varieties ‘Besni’, ‘Yuva’, ‘Midyat’ and ‘Semame’ and three melon cultivars ‘Ananas’, ‘Galia C8’ and ‘Galia F1’. The anti-oxidant capability of plants was determined by measuring ascorbate peroxidase (APX) and glutathione reductase (GR) activities together with levels of the anti-oxidant, ascorbic acid (AA). Salt treatment increased APX activities in stress-tolerant ‘Galia C8’ and ‘Galia F1’ and in moderately tolerant ‘Besni’, ‘Midyat’ and ‘Semame’. These increases were greater in salt-tolerant cultivars. On the other hand, salt treatment did not cause a significant increase in APX activity in the salt-sensitive cvs. ‘Yuva’ and ‘Ananas’. GR activity increased in all varieties and cultivars grown under saline conditions compared to control plants. Increases in GR activities were higher in salt-tolerant and moderately-tolerant varieties than in salt-sensitive ones. Likewise, AA contents increased with salt treatment in all varieties and cultivars except the salt-sensitive ‘Ananas’. The data indicate that melon seedlings respond to salt-induced oxidative stress by increasing both their enzymatic and non-enzymatic anti-oxidant defense systems. These increases were most clear in the salt-tolerant cultivars.

Effects of GA 3 Treatments on Ion Accumulation in Leaves of Pepper Plants Under Salt Stress

Experiments were conducted with Demre long pepper cultivar in a climate chamber with controlled climate parameters and in a hydroponic system with Hoagland nutrient solution. Three-week old seedlings were subjected to 100 mM NaCl treatments and samples were taken on 10 th day of the treatments for physiological and biochemical analyses. With the idea that gibberellic acid reduces negative impacts of salt on plants and regulates ion uptake, thus provide an ion balance, plants were also subjected to Gibberellic acid (GA 3 ) treatments at different doses (5ppm, 7.5ppm and 10ppm). Then, leaf samples were taken again on 10 th day of treatments and Na, K, Ca and Cl analyses were performed on samples. Present findings revealed that GA 3 treatments together with NaCl treatments recessed plant growth and development, but provided significant contributions in regulation of ion uptakes and providing an ion balance. The best GA 3 doses for plant growth and ion balance were identified as 7.5 and 10 ppm.