Physical and chemical treatments for enhancing seed germination of Oldman saltbush (Atriplex nummularia)

Abstract

This study was conducted to improve the seed germination of Oldman saltbush (Atriplex nummularia), which is an important fodder shrub commonly used for revegetation of degraded rangelands in the West Asia and North Africa regions. Seeds with and without their bracts (fruits) were subjected to physical (scarification, water soaking, gamma radiation) and chemical (potassium nitrate, sulfuric acid and gibberellic acid) treatments. For each treatment, sets of 100 seeds with and without bracts were selected randomly, divided into four equal groups, and incubated in a germinator at 20 ± 1°C. The treatments had a highly significant (P < 0.0001) effect on seed germination. The scarification, potassium nitrate (0.2% concentration), gibberellic acid (100 and 150ppm) and sulfuric acid (25% for 10min, 50% for 10 and 20min) treatments improved seed germination significantly compared to control treatment (4.0%). The different doses of gamma radiation and high concentrations of sulfuric acid (75%) reduced seed germination significantly (P < 0.001). The removal of bracts surrounding the seeds had a highly significant (P < 0.0001) effect on seed germination and averaged 73.5% for washing, 78.0% for scarification, 80.9% and 88.0% for potassium nitrate of 2% and 4% concentration, 88.1% for gibberellic acid of 150ppm, and 70.4% for sulfuric acid of 25% concentration. The results indicate that the inhibiting factors of germination must be located in the bracts. Future work should focus on developing technologies to remove the bracts surrounding the true seed of A. nummularia.