چکیده:
Haloxylon aphyllum is one of the most important species in sandy and saline areas in deserts, and some ecophysiology characters for viability in unfavorable condition have evaluated in this species. Seed germination is the critical stages in life cycle for species survival. In this study investigated salinity and temperature stresses on percentage and velocity of germination using six salinity treatments (0, 100, 200, 300, 400 and 500 mM/I NaCI) under four different temperature regimes (20:10, 30:10, 25:15 and 35:25 DC). The results showed that seeds could germinate at very high salt concentration (500mM). However, highest germination percentage was obtained in distilled water and thermoperiod 20:1cfc. Increased on salinity and temperature caused decreased of percentage and velocity of germination. Seed germinated rapidly and no significant change in germination was noticed after 10d. Recovery of seed germination investigated when seeds were transferred to distilled water. The results indicated that recovery percentage was high in seeds were transferred from very saline treatment with Lower temperature.
خلاصه ماشینی:
INVESTIGATION OF SEED GERMINATION CHARACTERISTICS AND RECOVERY OF GERRMINATION IN THE HALOXYLON APHYLLUM UNDER DIFFERENT TEMPERATURE AND SALINITY CONDITIONS A.
The results indicated that recovery percentage was high in seeds were transferred from very saline treatment with lower temperature.
Keywords: Haloxylon aphyllum, Salinity and temperature stress, Seed germination, Recovery of seed germination Introduction Deserts are regions with irregular precipitation regime and high evaporation potential.
In deserts, various ecophysiological characters and changes are seen in plants including life cycle (annual, perennial), vegetation form (brush, shrub), response to aridity (tolerance and avoidance from aridity), flowering period and kind of seeds distribution and germination (Fahn & Cutler, 1992).
After 20 days, other seeds that couldn't germinate under saline treatments were transferred to dishes having distilled water and recovery of seeds germination (RG) were 33 investigated in a 20 day period (equation 2) and showed in table 1.
5±37 500 These results showed that germination percentage under 25-35*c thermo periods (high temperature) was very low in all treatments but enhanced by increasing of salinity.
In many studies, Halophyte species had shown the same behaviors under saline environment including delaying in germination, decreasing of germination percentage and velocity and finally seed dormancy due to high osmotic pressure and shortage of available water (Ungar and Khan 1984, Pujol et at 2000 and Rubio-casal et al 2003).
In this study, in seeds transferred from saline treatment to distilled water, recovery of germination was investigated.