Effect of temperature on seed germination of two Callistemon species (Myrtaceae)

Abstract

The genus Callistemon belongs to the family Myrtaceae and comprises 34 species. They are woody aromatic trees or shrubs that are widely distributed in the wet tropics. According to the scientific literature, research on seed germination of this genus was rarely carried out. The germination requirements of Callistemon citrinus and Callistemon linearis were studied under controlled conditions in the laboratory. Seeds of both species were tested for germination at constant temperatures of 25°C, 30°C, 40°C, and at room temperature (23 ± 2°C) coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water) for 25 days of incubation. The kinetics of germination was determined according to four closely related parameters viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG) and time to 50% germination (T50). The room temperature of 23 ± 2 °C was found optimally suitable for both species, with 80% FGP and 11.1 days MGT for C. citrinus, and only 21.7% FGP and 12.4 days MGT were recorded for C. linearis. Furthermore, significant decrease in FGP was observed in both species at 25°C, 30°C and 40°C of temperature. The analysis also revealed that day 12-15 after seed sowing is suitable for final counts. Due of its very low FGP, seeds of C. linearis need an additional study to determine their viability.

Seed Germination of Scabiosa stellata (Caprifoliaceae), a Potential Medicinal Plant

“…Table 1 shows the influence of temperature on the germination kinetics of S. stellata seeds, with three stages: a first period of latency owing to imbibition, a second exponential period during which germination is accelerated, and finally a stationary phase. The distinctive behavior of S. stellata revealed that temperature had a substantial (p< 0.001) impact on seed germination potential.The temperature may affect the rate of germination by breaking dormancy and induce the germination process (Kigel, 2017;Kheloufi et al, 2020). Seed germination of S. stellata has been affected (p< 0.001) by temperature regimes and the number of days to count (Tab.…”