Allelopathic effects of leaf and corm water extract of saffron (Crocus sativus L.) on germination and seedling growth of flixweed (Descurainia sophia L.) and downy brome (Bromus tectorum L.)

This study was conducted in two factorial experiment based on completely randomized design with three replications at research laboratory of faculty of agriculture in University of Birjand in 2013. Factors included saffron organs at 2 levels (leaves and corms) and water extract concentrations at 5 levels (0، 0. 5، 1، 1. 5 and 2 percent). The allelopathic effects of saffron leaves and corms on seed germination and seedling growth characteristics of flixweed (Descurainia sophia L.) and downy brome (Bromus tectorum L.) were studied in two separate experiments. Results indicated lowest seed germination percentage of downy brome and flixweed were observed at concentration of 2% of corm extract (by 65% and 66% reduce compared to control، respectively). The rate of germination of downy brome decreased (by 71% compared to control) with concentration of 2% of leaf extract but the rate of germination on flixweed was not significantly affected by extract concentrations. Different concentrations of leaf and corm extracts significantly decreased length and weight of plumule and radicals of two weeds. A logistic model provided a successful estimation of relationship between leaf water extract and germination percentage of two weeds. Based on orthogonal comparison tests، the allelopathic inhibition effects of saffron leaves and corms were more on downy brome and flixweed، respectively.