Effect of temperature and water potential on Alyssum homolocarpum seed germination: Quantification of the cardinal temperatures and using hydro thermal time
Mohsen Zaferanieh, Batool Mahdavi, Benjamin Torabi
Abstract
This research was carried out to quantify the rate of Alyssum homolocarpum germination in response to temperature, and water potential. We compared three nonlinear regression models (Dent-like, segmented, and beta) to describe the germination rate-temperature relationships of Alyssum homolocarpum. The seeds were germinated at seven temperatures (5,10,15,20,25,30 and 35 °C) and six water potentials (0,-0.2,-0.4,-0.6,-0.8 and -1 MPa). The results revealed that the segmented function (RMSE = 0.28, R2 = 0.82, and r = 0.90) is suitable for describing the response to temperature, and water potential. Seeds did not germinate at 5 and 35 °C. Under different water potentials, base, optimum and ceiling temperatures ranged in 4.96 to 6.37 °C, 13.98 to 15.00 °C, and 28.7 to30 °C, respectively. The hydro time constant for SSG (θH), the middle value for the base water potential (Ψb(50), the standard deviation in base water in the water potential (σyb) and the thermal time constant for SSG (θT) spanned the values of 2.38–133.48 MPa h, −1.64–0.09 bar and 345.3–1477.3 °C h, respectively. The hydrothermal time parameters were 845.12 bar °C h, −1.114 MPa and, 57.3 °C for θHT (hydrothermal time constant), and Ψb(50) (median base water potential), Tb (base temperature) in temperatures and water potentials, respectively This low-temperature range for germination and the ability to germinate rapidly suggest the high potential of Alyssum homolocarpum to establish in most areas.