Using Halothermal Time Model to Describe Barley (Hordeumvulgare L.) Seed Germination Response to Water Potential and Temperature

Abstract

Barley (Hordeum vulgare L.) is a salt-tolerant crop with considerable economic value in salinity-affected arid and semiarid areas. In the laboratory experiment, the halothermal time (HaloTT) model was used to examine barley seed germination (SG) at six constant cardinal temperatures (Ts) of 15, 20, 25, 30, 35, and 40 °C under five different water potentials (ψs) of 0, −0.5, −1.5, −1.0, and −2.0 MPa. Results showed that at optimum moisture (0 MPa), the highest germination percentage (GP) was recorded at 20 °C and the lowest at 40 °C. Moreover, GP increased with the accelerated aging period (AAP) and significantly (p ≤ 0.05) decreased with high T. In addition, with a decrease of ψ from 0 to −0.5, −1, 1.5, and −2.0 MPa, GP decreased by 93.33, 76.67, 46.67, and 33.33%, respectively, in comparison with 0 MPa. The maximum halftime constant (θHalo) and coefficient of determination (R2) values were recorded at 20 °C and 30 °C, respectively. The optimum temperature (To) for barley is 20 °C, base Ψ of 50th percentile (Ψb (50)) is −0.23 Mpa, and standard deviation of Ψb (σΨb) is 0.21 MPa. The cardinal Ts for germination is 15 °C (Tb), 20 °C (To), and 40 °C (Tc). The GP, germination rate index (GRI), germination index (GI), coefficient of the velocity of germination (CVG), germination energy (GE), seed vigor index I and II (SVI-I & II), Timson germination index (GI), and root shoot ratio (RSR) were recorded maximum at 0 MPa at 20 °C and minimum at −2.0 MPa at 40 °C. Mean germination time (MGT) and time to 50% germination (T 50%) were maximum at −2 MPa at 40 °C, and minimum at 20 °C, respectively. In conclusion, the HaloTT model accurately predicted the germination time course of barley in response to T, Ψ, or NaCl. Therefore, barley can be regarded as a salt-tolerant plant and suitable for cultivation in arid and semi-arid regions due to its high resistance to salinity.

Effect of Jasmonic Acid Foliar Spray on the Morpho-Physiological Mechanism of Salt Stress Tolerance in Two Soybean Varieties (Glycine max L.)

“…Salinity is a major abiotic stress factor that adversely affects seed germination, plant growth, and productivity [35][36][37]. The phytohormone jasmonic acid (JA) can influence plant growth and development and regulates plant responses to biotic and abiotic factors [23,[38][39][40][41][42][43].…”

Validating the Impact of Water Potential and Temperature on Seed Germination of Wheat (Triticum aestivum L.) via Hydrothermal Time Model

“…Seed germination (SG) is a critical phase of plant development primarily affected by abiotic stressors [10][11][12][13]. Temperature and water potential have been determined to be major determinants of germination rate (GR), while other factors were not relevant for non-dormant seeds (Bradford 2002).…”

“…In order to understand how and why germination in various environmental conditions is affected, seedling growth models are employed. A number of studies have examined the effects of temperature (T), water potential (ψ), and the interaction between T × ψ on germinating seeds via thermal, hydrothermal, and hydrotime models [ 7 , 13 , 14 ].…”

“…For instance, Daucus carota [ 24 ], Plantago ovata Forssk. [ 25 ], Sinapis arvensis L. [ 26 ], Eruca sativa [ 7 ], and Hordeum vulgare [ 13 ]. To our knowledge, research regarding hydrothermal time validation for predicting wheat germination to different water potential and temperature levels is scarce.…”

Quantifying Temperature and Osmotic Stress Impact on Seed Germination Rate and Seedling Growth of Eruca sativa Mill. via Hydrothermal Time Model

“…The germination of seeds is a complex physiological phenomenon in the development of plants that is susceptible to abiotic factors including temperature, salinity, water potential, drought, and flooding [ 12 , 13 , 14 , 15 ]. Modeling seedling growth develops a quantitative description of how and why seeds germinate differently under various environmental conditions.…”