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 perennialastragalus species including a. effusus, a. vegetus, a. subsecundus, a. brevidens and a.cyclophyllon in the field conditions. seeds were sown after scarification with sandpaper byhand in the field of homand absard rangeland research station, damavand, iran in autumnin 2008. the seeds were sown using split plot design based on the completely randomizedblock design with three replications. in each plot, seeds of each accession were sown on twoparallel lines (scarified and control) with 2 m length and 75 cm along with the distance of 50cm for each accession. vegetation indices including forage production, canopy cover area,plant height, number of flowering stems and seed yield were studied over three years. datawere analyzed using split plot for specific years in sub plots and mean comparisons were doneby duncan method. results indicated significant differences between treatments, species andyears for all the traits. interactions between species and year were significant for all the traitsexcept plant height. seed scarification caused an increase in forage production, canopy coverarea and number of flowering stems. according to the results, mechanical seed scarificationhas been recommended to be done before planting herbaceous astragalus. the species a.vegetus (accession kurdistan) and a. effusus (accession urmia) were recommended for rangerevegetaion and rehabilitation in semi dry lands with the annual precipitation more than 300mm.