Improving Chilling Tolerance of Maize Seedlings under Cold Conditions by Spermine Application

Low temperature is an important abiotic stress which reduces crops growth and productivity and causes physiological damages to cellular structures. The aim of this study was to investigate the probability of spermine application to improve chilling tolerance of maize under stress conditions. The treatments were included seed priming with spermine (30, 60 and 90 mg/l solutions) and normal and stress condition. Seed emergence was improved by spermine priming on both conditions and mean emergence time (MET) was also decreased with priming. Shoot and root length was highly reduced under stress conditions, but the treated seeds were improved along with increased spermine concentration. Seedling dry weight was also affected by priming and reduced weight of stressful seedlings was alleviated by spermine priming. Decreased relative water content on seedlings under stress was elevated by the treatments and significantly increased. Electrolyte leakage was also recovered by applied treatments while it was adversely decreased on cold conditions. Antioxidative system was highly responded to spermine application. Superoxide dismutase (SOD) activity increased on both normal and stress conditions, but a little decrease was observed on seedlings treated with 90 ppm level and under chilling conditions. Catalase activity was also amplified by spermine treatments. Priming had a great effect on ascorbate peroxidase (APX) activity on both stressful and normal seedlings and increased it compare with non treated seedlings. It is also important to note that with increasing spermine concentration to 90 ppm, no considerable differences were observed. Thus, 60 ppm concentration could be proposed as the appropriate level of spermine in order to improve chilling tolerance of maize seedlings.