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EN
The photosynthetic characteristics of three kinds of leguminous forages were studied in a karst rocky desertification area of Guizhou using the photosynthetic apparatus on sunny days. The results showed that the curves of annual diurnal variation of the net photosynthetic rate and transpiration rate on three kinds of experiment forges showed different variation trends that were mainly related to the experimental materials. They showed that there were significant differences in the net photosynthetic and transpiration rates of different grasses, and also in photosynthetic physiology changes of different seasons. Through the annual photosynthetic physiological studies among Trifolium repens, Trifolium pretense, Medicago sativa, and other forage legumes can be concluded that the highest annual average net photosynthetic rate of leguminous forage was Medicago sativa followed by Trifolium repens, and Trifolium pretense was the lowest; the highest transpiration rate was Trifolium pretense followed by Trifolium repens, and the lowest was Medicago sativa, with little differences of this three leguminous forage. The highest photosynthetic efficiency and the lowest transpiration rate make the water use efficiency of Medicago sativa the highest, followed by Trifolium repens, and the lowest was Trifolium pretense. In most months, Trifolium repens, Trifolium pretense, and Medicago sativa were sensitive to high photosynthetic active radiation and high temperature, so taking a dormant form with closing their pores to reduce its water loss and material consumption. The primary productivity of grassland depends largely on water use efficiency. When establishing artificial grassland in the karst rocky desertification area we need to consider the net photosynthetic rate, transpiration rate, and water use efficiency, and take measures to use different kinds of forage, which not only reduce water loss but also improve water use efficiency and ease drought and water shortage in rocky desertification areas. From considering the overall perspective of annual photosynthetic physiological characteristics, Medicago sativa is more suitable than Trifolium repens and Trifolium pretense for the habitat conditions in light-moderate karst rocky desertification areas.
EN
To assess the effect of copper pollution meadow on grazing Wumeng semi-fine wool sheep and find an action plan to solve copper pollution, two experiments (grazing and sulfur supplementation) were conducted on copper pollution meadow at Wumeng mountainous area in Weining County of Guizhou Province. The contents of heavy metal elements were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) in soil, pasture, and animal tissues, and the blood parameter was determined by automatic blood cell analyzer. The results of grazing experiments showed that the content of copper and zinc in animal tissues when Wumeng semi-fine wool sheep grazed in the copper-polluted meadow were significantly increased (P<0.01), but the molybdenum content in animal tissues significantly decreased (P<0.01). At the end of experiment, the Hb, PCV, and RBC of the experimental Wumeng semi-fine wool sheep were significantly lower than control group (P<0.01), and mean corpuscular volume (MCV) was significantly lower than the control group (P<0.05), and the wool yield and length were significantly lower than not the control group (P<0.01). The results of the sulfur supplementation experiment showed that the supplementation of sodium sulfate significantly reduced the copper element content in blood and liver of Wumeng semi-fine wool sheep, the hemoglobin (Hb), packed cell volume (PCV), and red blood cell count (RBC) in blood of the experimental Wumeng semi-fine wool sheep were significantly higher than the control group (P<0.01), and the blood parameter reached the normal range at the end of the experiment. The content of copper element in blood and liver of the control group continued to increase, and the content of molybdenum in the animal tissues continued to decrease (P<0.01). The Hb, PCV, RBC, and MCV of the experimental Wumeng semi-fine wool sheep continued to decline, and hemolytic anemia was seen in Wumeng semi-fine wool sheep from control group at the end of experiment. However, sulfur supplementation had no significant effect on the relevant indicators of wool quality. Conclusion: copper pollution meadow seriously affect the mineral metabolism of Wumeng semi-fine wool sheep, and we can utilize the antagonism of sulfur and copper in the food chain to achieve the goal of harmless utilization of copper pollution meadow.
EN
Soil dust is one of the sources of PM₂.₅, and most soil dust is derived from bare soil. Our laboratory experiment was conducted to explore the effects of different mulching materials, including cobblestones (CS), green waste (GW), pine bark (PB), and organic mulching mats (OMM) on reducing the generation of soil dust from bare soil by different wind speeds near the ground (2 m/s, 4 m/s, 7 m/s, 9 m/s, and 12 m/s). The results showed that all 4 mulching materials reduced the generation of atmospheric soil dust. Both GW and OMM had the best effect at reducing dust generation when the wind speed near the ground ≤4 m/s, and OMM had the best effect when wind speed was >4 m/s. The mulching materials GW and PB could be completely blown away when the wind speed near the ground reached 7 m/s and 9 m/s, respectively. It appears that OMM is the best mulching material for covering bare soil in Beijing.
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