Measurement Of Nitrogen Utilization Efficiency And Mixed Seeding Advantage Of Mixed Pasture

To explore the generation mechanism of different mixed patterns on nitrogen utilization efficiency and mixed advantage of legume-grass,this study from mixed seeding grass growing efficiency,underground root system configuration and nitrogen use efficiency,etc,to carry out the research.Spatial distance and population effect were used as the variation factors of underground competitive environment.Using pot experiment to analysis and to compare the two kinds of forage grass' s relative growth rate,chlorophyll fluorescence parameters,herbage yield and relative yield,geometric morphology,topological structure and fractal characteristics of the root system and leguminosae herbage amount of nitrogen,nitrogen and nitrogen use efficiency under different mixed mode.Obtain the following main results:(1)The relative growth rate of two kinds of forage plant showed that the mixed sowing treatment was greater than mono-cropping treatment,and spacing 30 cm different line mixed treatment showed a higher relative growth rate;RDg value of B.innermis and RDl value of Onobrychis viciaefolia under different lines mixed seeding are both higher than that in peer mixed seeding,and spacing 30 cm different line mixed Onobrychis viciaefolia showed a higher RDl value and RY value,peering mixed seeding and spacing 30 cm different line mixed seeding showed a higher RYT value.The initial fluorescence efficiency Fo and maximal fluorescence Fm of Bromus innermis in mixed sowing treatment is higher than in mono-cropping treatment,and its PSII potential active center Fv/Fo value of mono-cropping treatment is higher than that in mixed sowing treatment.Under different mixed seeding method,the capture of light energy per unit area(TRo/CSo))values of two kinds of forage grass are smaller,and spacing 30/45 cm different line mixed treatment plant are both have higher chlorophyll fluorescence parameters.(2)Mixed seeding in different lines or increasing its row spacing increase aboveground biomass of the two kinds of grasses,and the root biomass and root cap ratio of bromus innermis is also increased,but the onobrychis viciaefolia is not obvious.Different lines mixed seeding + spacing increases make fine root(diameter?0.16 mm)of bromus innermis and the root(diameter 0.16~0.50 mm)of onobrychis viciaefolia increased,thus increasing the root length,root surface area and specific root length;Different lines mixed seeding + block makes the root diameter of two mixed seeding grass increasing,so as to make the root volume and specific root area increasing.Under different mixed seeding methods both grasses the topological index(TI)are close to 1,fixed topological index(qa)is greater than 0.5,the branching structure are the fishtail shape branches;With the increase of the space distance,there is a tendency for the topology of the roots of both grasses to a forked branch.Root length,root surface,root biomass and biomass on the ground are a linear positive correlation of two kinds of forage grass,and there is strong correlation between root biomass and other root morphology parameters,and poor correlation between root biomass and root cap ratio.(3)Spacing 30 cm different line mixed treatment showed a higher herbage yield than other mixed seeding treatments,and has high amount of application of biological nitrogen fixation and high nitrogen rate.Spacing 15 cm + mixed seeding treatment has high yield of N contribution rate.Nutrition competition ability of legume forage is stronger under the condition of different lines of mixed seeding than grass.Therefore row spacing of 30 cm + different line mixed treatment have high photosynthetic efficiency,high interspecific competition of legume forages,and biological nitrogen fixation and nitrogen rate,forming a stable component structure,high performance and high nitrogen using efficiency group.The spatial distance and population effect changed the competitive environment of underground root system of mixed group.The result of this plasticity is a developmental programme that is better able to cope with water and nutrients ecological adaptation strategy.