Effects of light and drought stress on germination of Artemisia sieberi Besser
Preservation and development of plant cover are major factors in the management of range ecosystems. Artemisia sieberi is one of the native dominant species of vast areas in the Irano-Turanian bioclimatic region. This species is very tolerant to drought stress and grazing pressure. Therefore, it can be used to rehabilitate degraded rangelands of dry areas within this region. Understanding the germination characteristics of this species is important for the conduction of revegetation projects. Seeds of A. sieberi were collected randomly from 20 plants of existing vegetation along 6 kilometers transect at Isfahan Kolah Ghazi National Park located at 51°45'E and 35°15'N. To pass the dormant period, seeds were pre-chilled for nine days at 0 to 5°C. Two germination experiments were conducted in complete factorial block design. Moisture stress test was carried out with 0, -0.2, -0.4 and -0.6 MPa treatments using polyethylene glycol (PEG) solutions in Petri dishes. The light treatment test was conducted with 12 h light and dark versus a continual dark condition. Results indicated that, an increase in the drought level lead to a decrease in the percentage and rate of germination, plumule length and allometry ratios, whereas the radicle length increased. In comparison with the dark treatment, 12 h of light treatment increased the percentage of germination and radicle length, while allometry ratios and plumule length decreased. Continual dark treatment compared with the 12 h light and dark photoperiod significantly reduced radicle and increased plumule lengths. Drought tolerance of A. sieberi seeds during germination showed the high potential of this species for vegetation rehabilitation in dry regions.
Key words: Artemisia sieberi, seed germination, drought tolerance, light treatments, Iran.