Seed germination is greatly influenced by both temperature (T) and water potential (Ψ) and these factors largely determine germination rate (GR) in the field. Quantitative information about T and Ψ effects on seed germination in lemon balm (Melisa officinalis L.) is scarce. The main objective of this study was to quantify seed germination responses of lemon balm to T and Ψ, and to determine cardinal temperatures in a laboratory experiment. A segmented model was used to describe the effects of Ψ (i.e., T) on GR and other germination parameters. The segmented model estimates were 7.2°C for base (Tb), 28.9°C for optimum (Tₒ), 40.1°C for ceiling temperature (Tc) and 1.64 physiological days (fₒ) (equivalent to a GRmax of 0.610 d⁻¹ and a thermal time of 35.6°C days) to reach 50 % maximum germination in the control (0 MPa) treatment (R²= 0.99, RMSE = 0.005 day⁻¹ ). The inherent maximum rate of germination (days) was calculated by the [GRmax = 1/fₒ] model. Ψ affected cardinal temperatures. From 0 to -0.76 MPa, when Ψ increased, Tb was a constant 7.2°C to -0.38 MPa and increased linearly to 20.1°C as Ψ decreased. Tₒ and fₒ increased linearly from 28.9 to 30°C, and from 1.64 to 5.4 day⁻¹ , respectively as Ψ decreased. However, there was no signification difference in Tₒ as Ψ decreased nor did Tc decrease from 40.1 to 35°C as Ψ decreased. Tb, Tc and GRmax were the sole parameters affected by Ψ and could be used to characterize differences between Ψ treatments with respect to GR at various Ts. Therefore, the segmented model and its parameters can be used in lemon balm germination simulation models.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.