Improvement of the seedling emergence method in soil seed bank studies using chemical treatments

Abstract

The seedling emergence method (SEM) is the most frequently used method for studying the soil seed bank. The main problem with this method is that it cannot provide a complete assessment of the seed flora present in the soil because its results are influenced by seed dormancy. In order to break seed dormancy of the soil seed bank, SEM can be combined with some chemical treatments. The objectives of this study were to determine the best chemical treatment which is able to overcome seed dormancy, and to study the effects of different chemical treatments on soil seedling emergence of different plant functional groups. Therefore, twenty soil samples were collected in the early spring in subalpine rangelands in northern Iran. Each soil sample was divided into four equal subsamples, and each subsample was treated by one of the dormancy-breaking treatments including gibberellic acid (GA3), hydrogen peroxide (H2O2), potassium nitrate (KNO3) and distilled water as control. The emergent species from the soil samples were categorized into functional groups, i.e., annual forbs, perennial forbs and perennial grasses. The results showed that the highest total seedling emergence was observed in the soil samples treated with GA3 (5465 seedlings/m2), whereas the lowest seedling emergence was found in the soil samples by KNO3 application (586 seedlings/m2). The perennial forbs were the only functional group that responded to all chemical treatments. We concluded that the use of GA3 for breaking seed dormancy can be useful for providing a more reliable estimation of the soil seed bank characteristics.