| Three stages of experiments have been taken in order to test the diversity of rhizosphere through different phosphorus efficiency maize inbred lines in conditions of different soil, levels of phosphorus and modes of pot culture.The experiment contains three parts.(1)Take root bag pot culture experiments on 6 maize inbred lines in red soil.(2)Choose 2 maize inbred lines that have the most diversity to do the experiments of normal root bag pot culture and upper-and-down-two-chamber-root-bag pot culture in red soil. (3)Take experiments of two-chamber-root-bag pot culture and three-chamber-root-bag pot culture in damp soil by using the same maize inbred lines as step 2.Numerous indexes were determined in the three experiments, such as the crop biomass, phosphorus absorption content, root configuration, rhizosphere acid phosphatase activity and pH. All the three experiments have measured the crop biomass, phosphorus absorption content, root configuration, rhizosphere acid phosphatase activity and pH. In the second experiment, we have added the determination of the activity of alkaline phosphatase. In the third experiment, we added the research of phosphate-dissolving bacteria on the basis of the two experiments below.The results of three experiments indicated that:1. In seeding stage, there were significant differences among different phosphorus efficiency maize inbred lines in aspect of biomass and phosphorus absorption in different soil. In different modes of pot culture and phosphorus levels, high-efficient-phosphorus maize inbred line is superior than the lower one in dry weight and phosphorus absorption content of the above ground parts and roots.2.There were also have significant differences in the two maize inbred lines, especially in the pot culture taken in damp soil and the root bag culture in red soil. Experiment of the root bag culture in red soil showed the most diversity: the length of roots and the quantity of root tips in high-efficient-phosphorus maize inbred line are nearly two times than the lower one.3.In seeding stage, rhizosphere phosphatase in different phosphorus efficiency maize inbred lines had certain changing trends. In experiments of pot culture in red soil and three-chamber-root-bag pot culture in damp soil, rhizosphere acid phosphatase activity in different phosphorus efficiency maize inbred lines showed obvious diversity: under the two levels of phosphorus, high-efficient-phosphorus maize inbred line is much higher than the lower one, and its influence range is much wider. Results of alkaline phosphatase in the following two experiments did not show significant differences.4.Rhizosphere pH also had significant differences in distinct phosphorus efficiency maize inbred lines. Under the two levels of phosphorus in two kinds of soil, rhizosphere pH declines in different levels. However, the high-efficient-phosphorus maize inbred line declines greater and the ability of acidization is higher.5.Diversity of phosphate-dissolving bacteria in different phosphorus efficiency maize inbred lines were significant differences. Experiment in damp soil shows that the quantity of phosphate-dissolving bacteria in rhizosphere soil of high-efficient-phosphorus maize inbred line is higher than that of the lower one. Differential value in the first layer reached nearly 30%. The quantity of phosphate-dissolving bacteria in near rhizosphere soil is two time than that of far rhizosphere soil.Above all, indices which are closely related with phosphorus absorption in high-efficient-phosphorus maize inbred line such as root length, quantity of root tips, root surface area, rhizosphere acid phosphatase activity, rhizosphere pH, quantity of rhizosphere phosphate-dissolving bacteria and phosphorus absorption content are superior than the lower one. |
