Productive Performance and Development Characteristics of Root Systems of 4 Forage Legume Species in Loess Plateau, China Effects of Nitrogen Addition on Competitive Ability and Productive Performance of Legume-Grass Mixture A Study of the Relationship Between Competitive Ability and Productive Performance of Spring Wheat in semi-arid Regions of Loess Plateau Study on the Productive Performance of Agropyron cristatum(L.) Gaertn.cv.Duerbote Effect of Basal Dressing Selenium and Cobalt Combined Fertilizer on Productive Performance of Alfalfa(Medicago sativa L.) A comprehensive evaluation of the productive performance of legume-grass mixtures under different mixed sowing patterns Effect of nutrition level on reproductive performance of Tan×Small Tail Han crossbred ewes