Bioassay study of saffron extract’s allelopathic effects on quantitative and qualitative traits of 4 medicinal species from labiatae family

According to the growth period of saffron, intercropping of this plant with species with similar needs can be a suitable option for better land use, provided that the allelopathy of this plant is considered. In order to investigate the allelopathic effect of saffron on quantitative and qualitative traits of some of medicinal plants, an experiment was conducted under greenhouse condition in ferdowsi University of Mashhad, Iran. Treatments were combination of 4 species (Thymus vulgaris, Zataria multiflora, Ziziphora clinopodioides and Teucrium polium and corm and leaf extracts in four levels (0, 3000, 6000, 9000 ppm) arranged in a completely randomized design with four replications. Measured parameters were fresh and dry weight of root and shoot, shoot to root ratio, stomatal resistance, SPAD reading and essential oil percentage and yield. Result indicated that interaction of corm and leaf extract concentrations affected fresh weight of root and SPAD reading. Four species showed different trends in different extract concentrations. In Thymus vulgaris and Zataria multiflora, with increasing extract concentration, stomatal resistance initially increased and then decreased but other species, other species did n’t follow this trend. In total species, with increasing extract concentration, SPAD reading, initially increased and then decreased. In all species studied, except Thymus vulgaris, as extract concentration increased shoot to root ratio increased. Also, with extract concentrations, essential oil percentage decreased. In general, in all investigated species, the physiological and qualitative traits of the plant decreased with the use of saffron leaf and corm extracts.