M.Sc. Tezi Görüntüleme

      In this study, indolacetic acid (IAA), gibberellic acid (GA) and abcisic acid (ABA) applied to maize seedlings and exposed to different temperatures between 5 - 45 oC for 24 and 96 hrs was examined to find out the changes total chlorophyll, chlorophyll a/ chlorophyll b (Chl a/b), free sugars (glucose, fructose and sucrose), total soluble carbohydrate and fatty acid with some enzyme (peroxidase and amylase) activities.

      Total chlorophyll content in maize seedlings exposed to low and high temperatures after the application of plant growth regulators (PGR) showed some incerases but not found significantly different. These increases in chl a/b ratios were clearly observed in ABA treatments. Seedlings with plant growth regulators sprayed (especially ABA) exhibited more healty morphological appearances when exposed to low and high temperatures.

      Generally, all plant growth regulators treated increased the level of fructose, glucose and sucrose, except ABA at low temperatures. Gibberellic acid was found to be more effective than the other hormones (IAA and ABA) to incresae sucrose level at low temperatures.

      PRG increased the level of 18:1, 18:2 and 18:3 acids significantly different (P=0.05). Besides the acids, the level of 16:0 and 18:0 acids decreased significantly both at low and high temperatures. ABA and GA treatments were found to be more effective than IAA treatment to increase the level of 18:2 and 18:3 acids.

      Generally, ABA and GA treatments increased the number of peroxidase izoenzymes in the seedlings exposed to short period of temperature regimes. A long period of cold treatment (96 h), IAA induced the synthesis of new peroxidase izoenzymes. At all temperature treatments, plant growth regulator treatments resulted in the synthesis of some amylase izoenzymes. Generally, IAA and ABA concentrations stimulated the formation of more izoenzymes.

      Keywords: Heat stress, Chlorophyll, Total soluble sugar, Free sugar, Fatty acid, Peroxidase, Amylase, Indolacetic acid, Abcisic acid, Gibberellic acid.