Survival and agronomic performance of 25 alfalfa cultivars and strains interseeded into rangeland

Abstract

This study assesses survival and agronomic performance of 7-year-old stands of 25 alfalfa (Medicago sativa L.) cultivars and experimental strains interseeded into rangeland near Mandan, N.Dak. Associated grasses consisted primarily of crested wheatgrass [Agropyron desertorum (Link) Schulte.], western wheatgrass [Pascopyrum smithii (Rydb.) Löve], needle-and-thread (Stipa comata Trin. & Rupr.), and blue grama [Bouteloua gracilis (H.B.K.) Lag.]. Soil was a Chama silt loam (Typic Haplustolls), an upland soil with moderate water holding capacity. Each entry was replicated 4 times in a randomized complete block design in plots consisting of 3 interseeded rows 6.1 m long with 90 cm between rows. Alfalfa cultivars and experimental strains with a high proportion of falcata [M. sativa subsp. falcata (L.) Arcang.] parentage were better adapted to interseeding into rangeland at a semiarid site in the northern Great Plains than traditional hay-type cultivars which have a high proportion of sativa (M. sativa L. subsp. sativa) parentage. Sativa-types with high levels of known winterhardiness had low survival in this test. Seven years after plant establishment, the 12 falcata-type entries averaged 100% more plants or propagules m-2, 124% wider foliage spread of plant rows, and 68% more dry matter yield, respectively, than the 13 sativa-type entries. Traits associated with falcata parentage such as plant spread by root proliferation and broad crown development, dormancy during midsummer drought, and slow, decumbent regrowth may help to enhance alfalfa survival in semiarid rangeland in the Northern Great Plains. These traits have no known utility in more humid environments where maximum forage yields from multiple harvests is a primary objective.