Reactions of sudangrass accessions to maize dwarf mosaic virus strain A and strain B

Abstract

Seventy-nine sudangrass (Sorghum sudanense (Piper) Stapf.) accessions obtained from foreign and domestic sources were inoculated with maize dwarf mosaic virus strains A and B. Sudangrass accessions were evaluated both in field and greenhouse tests to determine their reactions to infection, inheritance of resistance, and effect of virus infection on growth and yield. After inoculation at the 4 to 6 leaf stage of growth, symptom expression varied from mild mosaic to redleaf symptoms followed by necrosis. Resistant-to-susceptible plant ratios obtained from P1, F1, and BC1 generations indicate resistance to be a nondominant reaction which appeared to be controlled by more than a single gene. Relative height and tiller number between treatments of the 79 accessions was significantly reduced by the effect of the virus on plant metabolism. Relative dry weights of infected plants were reduced by as much as 38 percent by the virus infection. Four resistant sorghum x sudangrass hybrids were identified which would benefit growers and seed producers. As a result of the study, a world collection of sudangrass cultivars was established for future research.