Soybean Mosaic Virus Investigations with Susceptible and Resistant Soybeans1

Abstract

The soybean mosaic virus (SMV) susceptible soybean [Glycine max (L.) Merr.] breeding line D60‐9647 was inoculated with SMV‐1 at five different stages of development in each of 4 years to observe the effects of SMV in an area where vector dissemination of SMV is not apparent. Mean reduction in seed yield over the 4‐year period was 12%. Time of inoculation made little difference. There was a large increase in percent mottled seed following SMV inoculation with the highest percentage resulting from inoculation at the V7 stage of development. Percent of seedlings showing virus symptoms (15%) was highest from the inoculation at the V7 stage. Percentage of seed germination was reduced from 95 to 88%.Another study was conducted in which closely related SMV resistant and susceptible lines were compared using seed harvested from susceptible lines which had been inoculated with SMV. Seed yield of the susceptible lines, not again inoculated, did not differ from that of the resistant lines. Seed yield of SMV‐susceptible lines inoculated with SMV‐1 averaged 8% lower in seed yield than resistant lines in 1974 and 12% lower in 1975. The results indicate that under conditions similar to those in which our studies were conducted, seed from SMV infected plants can be utilized for planting with no undesirable effects.