The purpose of this study was to investigate the effects of different treatments on seed germination in the desert plant speciesCalotropis persica(Gand.). This species is known to have long time for seed germination considering arid region condition and short time of access moist. An experiment was performed with 13 treatments and 4 replications in a completely randomized design. Treatments included KNO3with concentrations of 0.1, 0.2, and 0.3 percent, immersion in hot water for five min, acetylsalicylic acid 100, 200, and 300 mg L−1, ethereal sulfuric acid (60%) for 5 and 10 min, thiourea with concentrations of 0.1% and 0.3%, and prechilling for 10 days. Tap water was used as the control. Our findings indicate that KNO30.1% and 100 mg L−1acetylsalicylic acid were the most effective treatments for improvement of seed germination properties in this species. In a comparison of the two mentioned treatment, KNO30.1% treatments is the best.
The main objective of this study was to investigate the spatial variation of heavy metals concentrations released by a Kurdistan cement plant and determine the level of soil and plant contamination with lead, chromium and cadmium around the cement factory in Kurdistan province and adjacent rangeland areas. Soil and plant (Astragalus gossypinus and wheat) sampling was undertaken along eight compass directions; samples spaced 500 m apart at 4500 m intervals along each direction from a location centered on the factory. After chemical digestion of samples, the concentration of the elements was measured using atomic absorption spectroscopy. Accumulation status and spatial variation of metals assessed at different distances from the factory (source of pollution) through two soil depths (0-15 and 15-30 cm). Results showed that soil layer depth, compass directions and distance from the factory signifi cantly affected the geo-accumulation of heavy metals in the soil. The bioaccumulation factor and translocation factor indicated that the lowest accumulation and transport rates of the pollutants in plant species are generally met, with both factors being below 1. The results also demonstrated that the highest amounts of Pb, Cr and Cd were in the surface soil (0-15 cm) at 60.86, 115.38 and 3.97 respectively, in the northerly direction. Spatial distribution of heavy metals was strongly infl uenced by the prevailing wind direction (from south to north). Heavy metal concentrations reported in this study are ascribed principally to the cement factory and its long years of operation and continual processing over nearly 25 years.
Aims Plants vary in their functional traits and thus in their preference towards edaphic conditions. Plants displaying tougher, long-living leaves, which better conserve nutrients in the tissues, are expected to grow better in acidic soils, which are frequently nutrient poor. Methods We used a trait-based approach, quantifying variations in the Leaf-height-seed (LHS) scheme and functional and phylogenetic indices in semi-arid communities from three different habitats (grasslands, shrubland and mixed habitats). Three traits, including specific leaf area (SLA), Plant height (H) and Seed Mass (SM), in 350 plots across the three habitats in the southern hillsides of Damavand Mountain. We only included the species that occurred in more than 20 plots throughout the dataset for the following analyses (i.e., 44 species). We calculated at the plot scale, community weighted means (CWM) for each trait, species richness, Faith’s phylogenetic diversity index (PD), functional richness (Frich), functional and phylogenetic mean pairwise dissimilarities (MPD) and nutrient concentration. Results The results showed that the higher soil nutrient concentration and pH were significant and positive related with species and functional richness and Faith´s phylogenetic distance, while not significant results were obtained for any functional trait at community level (SLACWM, VHCWM and SMCWM) or for the functional and phylogenetic mean pairwise distance.Conclusiones In addition, the phylogenetic and functional patterns responded more to the taxonomic richness variations than to trait-based assembly processes.
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