Effects of different input levels on weed seed bank in wheat fields of Mashhad

Species composition in weed seedbank was studied in low, medium and high input wheat fields. Two fields were selected for each input level based on the intensity of external inputs, e. g. chemical fertilizers, pesticides (in particular herbicides) and soil manipulation. Soil samples from 0-30 cm depth were taken systematically at 40 points in each field. Sampling was conducted in spring (early growing season) and autumn (end of growing season) and weed seeds in the soil seedbank were identified using standard methods. Total numbers of 18 weed species, mainly annual broad leaves, were extracted in three input levels and two samplings. Shannon diversity index (H) for weed seedbank was generally low (