Optimal temperature for germination of Zephyra compacta (Tecophilaeaceae)

Zephyra compacta is a geophyte plant endemic to Chile with the potential to be used as an ornamental crop. Its natural habitat is the coastal plains of the Atacama Desert, with a climate described as coastal desert with abundant cloudiness. This work analyzes the germination of Z. compacta seeds at 10, 15, 20, and 25 °C. Seeds were collected in 2011 and stored for 2 years and 4 months at 5 °C, until sowing. A mathematical model was used for germination analysis, p = A{1 − exp[−k(t − t₀)]}, where p is the germination percentage at a certain time t, A is the final germination percentage, t₀ is the estimated time of germination of the first seed, and k is the measure of the spread of the time to germination. Furthermore, the rate of germination of the median seed to germinate (1/t_A/2) was included. The germination curves showed a coefficient of determination (R²) between 0.86 and 0.99. The results show that temperature range for germination is from 10 to 20 °C, where A is over 90%. In this range, other evaluated parameters (t₀, k, and 1/t_A/2) show no significant difference, with the exception of k at 15 °C. At this temperature, germination is obtained in a shorter period of time and could be considered as the optimal temperature within the range. Finally, 25 °C is a supraoptimal temperature, where the value of A decreased to 30%.