Completion of the agronomic evaluations of Medicago ruthenica [(L.) Ledebour] germplasm collected in Inner Mongolia

Because Medicago ruthenica [(L.) Ledebour] is a potential new forage legume , we collected 90 accessions in Inner Mongolia in 1991. The 40 accessions e valuated in this study (E2) trace to 13 collection sites ranging from 40 de grees 40' (N) x 111 degrees 15' (E) to 42 degrees 55' (N) x 122 degrees 20' (E) and to altitudes ranging from 175 to 1493 m. Nineteen of these accessi ons were collected from new or under-represented sites in generally milder and drier climates (temperate desert steppes), compared to the 50 accession s evaluated earlier (E1). All accessions were evaluated at Beltsville, MD ( USA) on a B and K deficient Iuka sandy loam (coarse-loamy, siliceous, acid, thermic, Aquic Udigluvent; pH 6.4) in two-year studies. Significant variat ion was noted in E1 and E2 for dry matter yield, growth habit, leaf shape, and plant height and width. Upright growth habit and leaf narrowness, and p rocumbency and yield were positively correlated in both evaluations, but no particular leaf shape or growth habit was correlated with tolerance to win ter conditions. In E2, leaf:stem ratios of four M. ruthenica accessions and a cultivated alfalfa (M. sativa L.) check were not significantly different , but M. ruthenica was significantly more tolerant of potato leafhopper (Em poasca fabae Harris) feeding than was M. sativa. Second-year alfalfa dry ma tter yield was about five times larger than that of M. ruthenica. Many of t he highest yielding accessions were collected near cultivated fields and/or buildings. Although data for both evaluations demonstrated the same basic trends, there were sufficient deviations to emphasize the value of evaluati ng the entire germplasm collection.