Germination characteristics of Agriophyllum squarrosum

Agriophyllum squarrosum (L.) Moq. (Chenopodiaceae), a pioneer species of natural succession in semi-arid regions of China, is widely used for vegetation rehabilitation by air seeding. Experiments were conducted to determine the effects of light intensity and photoperiod, as well as constant and alternating temperatures, on germination to improve the technology of air seeding. Seed of A. squarrosum rarely (<18.5%) germinated at 5/15, 10/20, 15/25, and 20/30 °C (night/day); 39.5% of seeds germinated at 25/35 °C in a 14-h (215 μmol•m(-2)•s(-1)) photoperiod. Under dark conditions there was a high final percent seed germination (>90%), except for 71.8% final percent seed germination at 5/15 degreesC. Constant temperature conditions were associated with lower seed germination (<50%). Less than 13% of seeds germinated at different light intensities (25-400 μmol•m(-2)•s(-1)) at 10/20 °C. There was no significant difference in final percent germination when seeds were exposed to 400, 100, or 25 μmol m(-2) s(-1) for 2 h daily. Final percent germination and germination rate deceased rapidly when the photoperiod was increased under 400 μmol•m(-2)•s(-1). Only 49.2% of seeds germinated after 3 d. Because of the deleterious effect of light on germination, air seeding in late May is recommended.