Quantifying seed germination response of deteriorated Trigonella foenum-graecum L. seed to temperatures and water potentials: Thermal time, hydrotime and hydrothermal time models

Abstract

Quantifying the germination behavior of seeds against variable environmental conditions can use as a useful implement for seed ecological studies. Seed vigor depends on the temperature and moisture conditions during seed development and storage. To quantify the effects of temperature and water potential on germination response of fenugreek seeds, thermal time, hydrotime, and hydrothermal time models were employed. The treatments included 9 temperatures (5, 10, 15, 20, 25, 30, 35, 40 and 45 °C), and five water potentials (0, −0.2, −0.4, −0.6, and −0.8 MPa) on deteriorated (35 h) and non-deteriorated seeds. The results indicated that the segmented model was the best model to describe the germination response of fenugreek seed under different temperatures and water potentials. The cardinal temperatures predicted for germination were 0.48, 21.6, and 46 °C for non-deteriorated seeds, and 0.85, 20.6, and 46.3 °C for deteriorated seeds at 0 MPa. Thermal time constants were 49125 and 56657.9 °C h for non-deteriorated and deteriorated seeds at -0.8 MPa and were 899.6 and 1072 °C h for non-deteriorated and deteriorated seeds at 0 MPa. Hydrotime constants were 50.64 and 72.37 MPa h at 5 °C for non-deteriorated and deteriorated seeds and were 1.97 and 3.07 MPa h at 35 °C. Hydrothermal time constants of non-deteriorated and deteriorated seeds were 264.1 and 263.1 MPa °C h at the supra-optimal temperatures.