Researches Of P-containing Nanosized Phosphate Materials Using As Solid P Sources In Hydroponic Culture And Using As Solid-phase Extractor

Phosphorus is a kind of the mineral resource which is non-renewable. As one of the essential elements that plants need in the vegetative process, phosphorus is an obbligato chemical fertilizer in agricultural production. It has an irreplaceable function in the ecosystem, which people need to live by. However, in the condition of high phosphorus content, the leaves of the plants may have a deep accumulation of inorganic phosphorus, which affects the rate of transpiration and photosynthesis. Especially in the condition of hydroponics, it’s a must to imitate phosphorus concentration of real soil solution, and to maintain the relative constancy of nutritive element concentration for the root environment of the plants. Thus, the initial concentration of nutrient substance is higher than the phosphorus concentration of the soil solution. Nonetheless, directly putting high concentration of dissoluble phosphorus into the nutrient solution may lead to the toxic action to the plants. In order to make the accordance of the phosphorus concentration of the nutrient solution and extractive soil solution from soil sample, to keep the low content avoiding the toxic action, this experiment attempts the feasible method which is putting the solid P sources into the nutrient solution to slowly release phosphorus so as to keep the low concentration level.The thesis tries to start two experiments:the first one is to grow barley using the method of hydroponics, with phosphorus containing nanophosphate as the solid phosphorus source; the second is to determinate organic acids with the phosphorus-containing nanophosphate as solid-phase extractor.Ⅰ. The research on hydroponic barley with phosphorus-containing nanophosphate as the solid phosphorus sourceThis thesis makes use of phosphorus-containing nanophosphate as its solid phosphorus source to produce barley with hydroponics. It finds the mobilization and utilization of phosphorus-containing nanophosphate with the aid of organic acids secreted from the root system of barley, and then discuses the feasibility of using solid phosphorus source to produce hydroponic plants. In the experiment, there is a comparison among bulk-hydroxyapatite (THAP), nano-hydroxyapatite (NHAP) and amorphous calcium phosphate (ACP).The experiment studies the phosphorus content in the nutrient solution and the barley, the biomass, the micronutrient level, the system of antioxidant enzyme, the content of malondialdehyde and chlorophyll. The research result shows that the dissolving capacity of ACP is higher than NHAP and THAP, and the phosphorus the ACP release can be absorbed and utilized by barley. When the same amount of the three substances are applied to the barley leaves, the rule of fresh weight is:ACP>NHAP>THAP. With the same amount of the three substances, the rule of CAT and the activity of POD is THAP>NHAP>ACP; with the same amount of the three substances applied in the overground part, the rule of the activity of SOD is:ACP>NHAP>THAP. The lack of phosphorus can lead to the increase of MDA. In the research of lacking phosphorus, the content of MDA is relatively high. When the same amount of the three substances are applied in the barley, the overall rule of chlorophyll A is:ACP>NHAP>THAP.Ⅱ. The research on determination organic acids with ACP as solid-phase extractorThrough the condition of solid-phase extraction, such as optimization of adsorption and elution, ACP selectively assimilates the oxalic acid and conducts the quantitative recovery. It effectively avoids the hurt of nitrate to the oxalic acid, when the reversed-phase high-performance liquid chromatography analyzes the bleeding sap of xylem. The thesis uses the method of solid-phase extraction to get the oxalic acid from the bleeding sap of pokeweed xylem, with the aid of ACP powder. And then the experiment will show the content of oxalic acid. Compared with the previous researches, this one shows that ACP has a stronger extracting power.0.03g ACP powder can completely extract the oxalic acid of initial PH3. Under the alkaline condition, ACP still has a strong adsorption capacity. The oxalic acid extracted can be eluted by100mmol/L (NH4)2HPO4solutions. The adding standard recovery of RP-HPLC is ranged from96.2%to100.2%. This method can accurately analyze the content of oxalic acid from the bleeding sap of pokeweed xylem. What’s more, such an analysis can be applied to other plant samples.