Heavy metal pollutants are the main concern of new agricultural productions. Industrial products and using synthetic materials leads to drastically increase in concentration of different heavy metals in the environment. Lead and Cadmium are two famous heavy metals which are largely used in electronic industries thus the waste water of factories could pollute agricultural lands. Different heavy metal solutions were investigated for their effects on seed germination characteristics and phytoremediation potential of two oil crops ( canola, Brassica napusandsafflower, Carthamustinctorious) and a cereal crop (wheat, Triticumaestivum). The Canola, Safflower and Wheat seeds were germinated after treatments in solutions containing varying concentrations of heavy metals. Five different concentrations of heavy metals including (BiNO3, BiNO3, CdNO3, Sr (NO3)2, ZnNO3) at 50, 200, 350, 500, 1000 ppm and distilled water considered as control treatment. Results showed that in all treatments the percentage of seed germination, root and shoot length decreased as concentrations of solution increased. No germination was observed at 1000 ppm of cadmium level. Root and seedling vigor increased by application of 200 ppm of BiNO3. There were no seedling growth at 350 and 500 ppm of cadmium and lead concentration.
Seed germination under field conditions is highly influenced by the presence of other plants. Allelopathy is an important mechanism of plant competition, by producing phytotoxins to the plant environment in order to decline other plants' growth. Soil sickness problem in farm lands is also known as an allelopathic effect or even autotoxicity. The toxicity of released allelochemicals by a plant in the environment is attributed to its function of concentration, age and metabolic stage. In this study we investigate the effect (5, 20, 35 and 50 g l -1) of leaf, stem and root water extract of sorghum on seed germination and seedling growth of mung bean. The results of the experiment showed that allelopathic effect of different concentrations was not significant for germination percentage, but germination rate and mean germination time decreased significantly by increasing the concentration of allelopathic extracts; also, there was a clear allelopathic effect of sorghum extract on seedling growth of mung bean. 50 g l -1 sorghum stem extract exhibited the highest inhibitory effect on root and shoot growth of mung bean. Among all parts of sorghum, stem extracts showed the highest allelopatic effect on seedling growth. Root extract showed higher inhibitory effect than leaf extracts.
Previous studies suggested that fast and uniform germination is important for good crop establishment. The present study was conducted to investigate the possibility of increasing germination characteristics by seed priming techniques. An experiment was conducted with three replicates and two treatments including: 2 different priming duration (8 and 12 hours) and 6 osmotic potential of PEG 6000 solutions (-0.8, -1,-1.2,-1.4,-1.6 Mpa) and distilled water as a control group). The priming solutions were prepared using polyethylene glycol 6000 (PEG). Our results showed that the most effective osmotic potential in improving germination characteristics of Trifolium alexandrium is -0.8 MPa for 16 hours.
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