Effect of seed priming on germination characteristics, polyphenoloxidase, and peroxidase activities of four amaranth cultivars.

Abstract

Amaranth is a C 4 crop with increasing potential for cultivation in Iran. Amaranth is a very nutritious crop due to high quality amino acids and minerals in its seeds. Seed priming known as pre-sowing treatment which improve germination characteristics and results in uniform seed emergence. Peroxides (POD) and polyphenoloxidase (PPO) are two plant enzymes and play very important role in tolerance to environmental stress. Four amaranth cultivars from two genuses, namely, Amont, Trigin, Mercado, and Plainsman were used. Treatments consisted of four osmotic potentials (0, -10, -12 and -14 bars) and four treatments duration (3, 6, 9 and 12 hours). A randomized completely design with five replications were conducted. POD and PPO activities were determined in primed (-10 bar for 3 hours) and non-primed seeds after 8 hours of imbibitions. Results indicated that the best priming treatments for amaranth cultivars were -10 bars for 3 hours. According the results of this study, primed seeds significantly exhibited higher germination percentage, speed of germination, root length and seed vigor in all amaranth cultivars. Trigin cultivar showed the best performance among cultivars. Total seed protein, POD and PPO were also increased significantly by seed priming. Amont and Plainsman cultivars exhibited high protein content and POD activity. PPO activity increased by seed priming comparing to controls for Amont, Plainsman and Mercado cultivars, but for Trigin cultivar, no increase was detected. The highest increase in PPO activity was observed in Mercado cultivar.