Biochemical changes stimulated by accelerated aging in safflower seeds (Carthamus tinctorius L.)

Abstract

Seed vigor tests are used to estimate their quality. One of the most commonly used is the accelerated aging test (AA). The aim of the present study was to study the biochemical changes caused in the seeds and to determine their germination status after the AA. Six safflower genotypes were tested at 43 °C and 45 °C for 0, 48, 72, 96 and 120 h, and germination percentage (GP), mean germination time (MGT) and normal seedling percentage (NSP) were evaluated to determine the aging reactions of the genotypes. During the AA at 45 °C, the seeds quickly lost their germination ability after 48 h; after 120 h, the seeds lost their viability, remaining, however, still viable at 43 °C. Two genotypes that aged more (Linas and Olas) and less (Bayer-6 and Bayer-12) were chosen to examine the biochemical changes during the AA at 43 °C. Eleven biochemical analysis were performed to understand physiological changes associated with the test. Total caratone, xanthophyll, phenolics, flavonoid, soluble protein, soluble sugars, oil and malondialdehyde contents were lower after 120 h, compared to 0 h. Reducing sugars and free fatty acids contents increased in the least and most aging genotypes. However, the total tocopherol content increased in the least aging genotypes and decreased in the most aging genotypes after 120 h, compared to 0 h. The results showed that the AA at 43 °C was suitable to study the aging process in the safflower seeds. Besides, understanding the chemical changes was useful to elucidate the physiological basis of seed aging.

Determination of Hydrogen Peroxide Content and Antioxidant Enzyme Activities in Safflower (Carthamus tinctorius L.) Seeds After Accelerated Aging Test

“…The results of germination parameters such as; percent germination, mean germination time and normal seedling percentage after AA for safflower genotypes were published previously [20]. Results of germination tests indicated that AA test at 43 °C was favorable to assess the effects of aging in safflower since germination at specified time and temperature distinguished aging resistant and sensitive genotypes.…”

“…In seed aging studies, ROS-like H2O2 plays a very important role in oxidation of all molecules found in cellular structures [7,33]. Enzymatic lipid peroxidation, H2O2 accumulation and the formation of free radicals may be the main cause of seed degradation in oilseed plants such as safflower [20,34].…”

“…The safflower genotypes (Bayer-6, Bayer-12, Linas and Olas) were used as seed materials. Adjustment of seed moisture content before and after surface sterilization, performing of AA tests, germination conditions were given in a previously published study [20]. Seeds of control treatment (0 h) were not exposed to aging conditions.…”

“…Seeds of control treatment (0 h) were not exposed to aging conditions. These genotypes were differentiated based on their reaction to AA in a previous study and classify as aging resistant and sensitive [20]. Seeds were stored at 4 °C until the analyses.…”

“…There is a need to investigate the role of antioxidant enzymes in seed aging with AA testing and to examine the changes in the activity of antioxidant enzymes at different aging times. Oxidative lipid peroxidation was not the main reason of seed degradation during AA in safflower seeds [20]. Therefore, present study was carried out to investigate hydrogen peroxide (H2O2) accumulation and antioxidant enzyme activities (CAT, SOD and POD) between aging resistant and sensitive genotypes of safflower during the AA.…”