Effect of Seed Aging and Water Potential on Seed Germination and Biochemical Indices of Fenugreek (Trigonella foenum-graecum) at Different Temperatures

Introduction: Seed germination is one of the most important and complex stages in the plant life cycle and is affected by many hereditary and environmental factors. Various factors affect germination and seedling establishment. Among these factors are the characteristics of the maternal plant (nutrition, genetics), seed treatment stage at harvest time as well as environmental factors (temperature, water potential, and ventilation and soil compaction). In addition, under the influence of seed loss during storage, seed vigor, which is known as the first component of seed quality, decreases. The aim of this study was to investigate germination and biochemichal responses of the aged seeds of Fenugreek to different temperature and humidity ranges. Materials and Methods: This experiment was conducted as a factorial based on a completely randomized design with four replications in the Laboratory of Seed Science and Technology, Faculty of Agriculture, Yasouj University in 2016. The experimental treatments consisted of nine levels of temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 degrees Celsius), water potential comprised seven levels (zero (control), -0.2, -0.4, -0.6, -0.8, -1 and -1.2 MPa) and seed aging at two levels (no aged (control) and aged seed). Results: In this experiment, the effect of seed aging, water potential and their interactions in each environment on germination indices (germination percentage and germination rate, length and weight vigor index) and biochemical indices (soluble sugar, proline, soluble protein and catalase enzymes) of Fenugreek seeds were significant. The results showed that in the aged seeds, the germination percentage and rate and seedling vigor index tended to decrease with water potential reduction at temperatures below and above 20 degrees Celsius, whereas the amount of biochemical components of the seeds (soluble sugar, soluble protein, proline, and catalase enzyme) increased. Conclusion: In general, germination and biochemical indices of seeds of Fenugreek are sensitive to water potentials, aging, and seed germination temperatures, respectively. In case of reduction in osmotic potential, the germination temperature less than 20 °C resulted in increased germination resistance of fenugreek seeds to a more negative water potential.