Effects of Seed Scarification on Vegetation Parameters in Some Astragalus Species under Field Conditions (Case Study: Homand Absard, Damavand, Iran)

This research aims to evaluate the effects of seed scarification on five perennial Astragalus species including A. effusus, A. vegetus, A. subsecundus, A. brevidens and A. cyclophyllon in the field conditions. Seeds were sown after scarification with sandpaper by hand in the field of Homand Absard Rangeland Research Station, Damavand, Iran in autumn in 2008. The seeds were sown using split plot design based on the completely randomized block design with three replications. In each plot, seeds of each accession were sown on two parallel lines (scarified and control) with 2 m length and 75 cm along with the distance of 50 cm for each accession. Vegetation indices including forage production, canopy coverarea, plant height, number of flowering stems and seed yield were studied over three years. Data were analyzed using split plot for specific years in sub plots and mean comparisons were done by Duncan method. Results indicated significant differences between treatments, species and years for all the traits. Interactions between species and year were significant for all the traits except plant height. Seed scarification caused an increase in forage production, canopy cover area and number of flowering stems. According to the results, mechanical seed scarification has been recommended to be done before planting herbaceous Astragalus. The species A. vegetus (accession Kurdistan) and A. effusus (accession Urmia) were recommended for range revegetaion and rehabilitation in semi dry lands with the annual precipitation more than 300 mm.