Determination cardinal temperatures of vetch (Vicia sativa; Vicia pannonica) in response to temperature and different water potential using segmented model

This study was conducted to study germination two species of vetch (Vicia sativa; Vicia pannonica) under temperatures (5, 10, 15, 20, 25, and 30 °C) and different water potentials (0, -2, -4, -6, -8 and -10 bar) at the Vali Asr Rafsanjan University laboratory in completely randomized design arranged as a factorial with four replications. The segmented function was evaluated to describe the relationship between germination rate and temperature. Results showed base temperature for germination of Vicia pannonica was -3.65 to 1.39, optimum temperature 23.99 to 25.57 and ceiling temperature 30 to 58.54 under different water potentials. The biological hours for germination of this specie were 32.29 to 74.97 hours under different water potentials. Also, base temperature for germination of Vicia sativa was -3.54 to 1.39, optimum temperature 22.70 to 25.64 and ceiling temperature 30 to 42.28 under different water potentials. The biological hour requirements for germination of this specie were between 33.10 to 83.54 hours under different water potentials. The results of germination rate in both species showed that with increasing water potential, germination rate decreased. In all of water potentials germination rate increased to 25°C and then decrease. Estimated parameters and the relations can be used to prediction time to germination or emergence in two species of vetch under different water potentials.