Effects of seed collecting date and storage duration on seed germination in Artemisia spp.
Artemisia genus (Asteraceae) includes approximately 400 and 33 species in the world and Iran, respectively. The species have medicinal properties and is widely distributed in arid and semi-arid regions. Low seed germination due to some phenolic compounds especially in collected fresh seeds of Artemisia spp. has been reported. The objective of this study was to determine the effect of seed collecting dates (5 to 6 times from mid-November to early January, 10 days intervals) and seed storage duration (4, 8, and 12 months) at room temperature on seed germination of four Artemisia species (Artemisia sieberi, A. diffusa, A. kupetdaghensis, and A. aucheri) collected from ten different locations in north east of Iran during two years. The experiment was conducted as a completely randomized design with four replications and combined analysis was done as cross-nested design. The results showed that there were significant differences between seed collecting date for each site and seed storage duration and their interactions (P < 0.01). Seed storage duration had higher effect on seed germination than collecting date. Overall, mean seed germination percentages were 37.24, 29.07, 44.69, and 62.84% at 0, 4, 8, and 12 months storage, respectively (P < 0.01). The regression model for relationship between final germination percentage (y) with storage duration (x) was fitted (y = 36.18 - 2.62 x + 0.41x2, R2 = 96.4%). The results suggest that delay in seed collecting at late November through early December and seed storage durations of 8 or 12 months improved seed vigor and germination rate of Artemisia spp.
Key words: Artemisia spp., seed germination, seed collecting, storage, regression model.