Physiological Responses Of Italian Ryegrass To Piggery Wastewater And Purification Of Piggery Wastewater With The Grass

Due to the enlarging scale of intensive livestock, the increasing discharge amount of piggery wastewater aggravated environmental pollution. Italian ryegrass(Lolium multiflorum L.) are widely cultivated as forage in the agricultural region of China. With the advantages of strong regrowth habits, a great amount of roots, rapid growth and so on, Italian ryegrass be considered used to purify the polluted environment. The effects of piggery wastewater on the seed germination, the growth and physiological characteristics of Italian ryegrass in the seedling and tillering stages were determined. Moreover, the purification effect of Italian ryegrass in the seedling and tillering stages on piggery wastewater was also studied in a pot experiment. The results were summarized as follows:1. After the seeds of Italian ryegrass were immerged in the piggery wastewater with different concentration for 20 minutes, seed germination and root elongation of seedlings were higher than that of control.2. The results showed that the seed germination, leaf and root elongation of seedling were significantly inhibited by irrigation treatment method with different concentration of piggery wastewater. The inhibition rate of root growth was greater than that of leaf growth. No seed germinated under the concentration of 800/200mg/L (TAN/TP).3. Compared with the control, the biomass of above ground parts of Italian ryegrass was increased, but root growth was inhibited at seedling and tillering stage by treatment of piggery wastewater. The root length of plants at seedling and tillering stages was 30.0% and 72.8% of control, respectively, under the concentration of 200/50mg/L (TAN/TP) of piggery wastewater. However, the root growth of plants at seedling and tillering stage was completely inhibited when the concentration of piggery wastewater over 800/200mg/L (TAN/TP).4. With the treatment time of wastewater culture increasing, chlorophyll content increased of plants. Furthermore, the activate oxygen metabolism system was destroyed. POD activity of plants tend to increase. MDA content of plants tend to increase in tillering, but to decreased in seedling stage.5. The content of nitrogen and phosphorus of plants treated with piggery wastewater was significantly higher than that of control. Nitrogen and phosphorus contents in stem and leaf were significantly higher than that in root.6. After the purification treatment by Italian ryegrass or natural standing, the nitrogen contents in piggery wastewater was decreased. However, the purification effects on nitrogen and phosphorus in piggery wastewater by Italian ryegrass treatment was better than that of natural standing.There was no significant difference observed on phosphorus content in piggery wastewater before and after natural standing. However, phosphorus content was decreased by Italian ryegrass culture obviously. The purification efficiency of phosphorus by Italian ryegrass was 2 times higher than that by natural standing when the concentration was 200/50mg/L (TAN/TP).In conclusion, tillering stage was the optimum growth stage for Italian ryegrass to purify the piggery wastewater with the concentration of 215/50mg/L(TAN/TP).