Hydrothermal time analysis of watermelon (Citrullus vulgaris cv. ‘Crimson sweet’) seed germination

Bakhshandeh, Esmaeil; Atashi, Sadegh; Hafeznia, Maryam; Pirdashti, Hemmatollah; Teixeira da Silva, Jaime A.

Hydrothermal time analysis of watermelon (Citrullus vulgaris cv. ‘Crimson sweet’) seed germination

2015

Bakhshandeh, Esmaeil | Atashi, Sadegh | Hafeznia, Maryam | Pirdashti, Hemmatollah | Teixeira da Silva, Jaime A.

This study evaluated the ability of a hydrothermal time model (HTT) to describe the kinetics of watermelon (Citrullus vulgaris cv. ‘Crimson sweet’) seed germination under different temperatures (T) and water potentials (ψ) and also to determine the cardinal temperatures of watermelon. Results indicated that ψ influenced germination rate and germination percentage. For this seed lot, cardinal temperatures were 10 °C for Tb, 28.34 °C for Tₒand 40.8 °C for Tcin the control (0 MPa) treatment. There was a decrease in hydrotime constant (θH) when T was increased to Tₒand then remained constant at supra-optimal temperatures (30 MPah⁻¹). Also, at temperatures above Tₒ, ψb₍₅₀₎values increased linearly with T. The kTvalue (the slope of the relationship between ψb₍₅₀₎and T exceeds Tₒ) of this seed lot was calculated as 0.076 MPa°Ch⁻¹. Results this study show that when the HTT model is applied, it can accurately describe ψb₍g₎and the course of germination around Ts (R² = 0.82). Moreover, the ψb₍₅₀₎was estimated to be −0.96 MPa based on this model. Consequently, the germination response of watermelon for all Ts and ψs can be adequately described by the HTT model and enabling it to be used as a predictive tool in watermelon seed germination simulation models.

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