EFFECTS OF BARLEY YELLOW DWARF VIRUS ON ROOT AND SHOOT GROWTH OF WINTER-WHEAT SEEDLINGS GROWN IN AEROPONIC CULTURE

Seedlings of eight soft red winter wheat (Triticum aestivum) cultivars were grown in an aeroponic mist box to study the effects of barley ye llow dwarf virus (BYDV) on root and shoot growth and to look for diffe rences in root and shoot growth among cultivars. The cultivars selecte d for the study were Caldwell, Cardinal, Clark, Howell, IL 87-2834, Ty ler, and Pioneer brands 2548 and 2555. A split-plot treatment design w as used, with uninfected and inoculated treatments as whole plots and cultivars as subplots. Differences among cultivars were found for most growth characteristics under both control and BYDV-infected condition s. There was a strong positive correlation between shoot and root dry weights in both the control and BYDV treatments, indicating that culti vars with vigorous shoot growth tended to have more vigorous root grow th. BYDV severely reduced root length, distance from seminal root tip to the nearest lateral root, and the root to shoot ratio for all culti vars tested. The number of adventitious roots and shoot percent dry ma tter were increased by BYDV infection for some cultivars. Chlorosis an d stunting were not observed in shoots during the 18 days of the exper iment, whereas roots were visibly stunted approximately 4 days after i noculation. Results indicate that, initially the root system is affect ed more severely than the shoot in BYDV-infected wheat seedlings.