Using Some Growth Retardants for Inhibition of Maize Dwarf Mosaic Virus (MDMV)

The current study was carried out to evaluate the effect of some growth retardants such as alar, ethrel, cycocel and paclobutrazol with different concentrations (50, 100, 150 and 200 ppm.) on maize dwarf mosaic virus (MDMV) in vitro and in vivo. In vitro experiment, growth retardants reduced the occurrence of mosaic symptoms on maize plants. These percentages were reduced to 40%. Paclobutrazol was the most effective treatment giving mosaic symptoms percentages reached to 48, 44, 44 and 40 % when used with concentrations of 50, 100, 150 and 200 ppm respectively. On a statistical basis, paclobutrazol caused a significant reduction in the mosaic symptoms percentages when used with a concentration of 50, 100, 150 and 200 ppm. While cycocel caused a significant reduction in the mosaic symptoms percentages, only, when used with a concentration of 200 ppm. So, paclobutrazol and cycocel was more effective in reducing the mosaic symptoms produced by MDMV on maize plants than other treatments. In preinoculation experiment, all tested growth retardants reduced the mosaic symptoms percentages. These percentages were reduced to 32%. Paclobutrazol was the most effective treatment giving mosaic symptoms percentages reached to 40, 36, 36 and 32 % when used with concentrations of 50, 100, 150 and 200 ppm respectively. On a statistical basis, paclobutrazol and cycocel caused a significant reduction in the mosaic symptoms percentages when used with a concentration of 50, 100, 150 and 200 ppm. While ethrel caused a significant reduction in the mosaic symptoms percentages, only, when used with a concentration of 200 ppm. In post-inoculation experiment, all tested growth retardants reduced the mosaic symptoms percentages (infectivity of MDMV). These percentages were reduced to 40%. Paclobutrazol was the most effective treatment giving mosaic symptoms percentages reached to 56, 52, 52 and 40 % when used with concentrations of 50, 100, 150 and 200 ppm respectively. On a statistical basis, paclobutrazol caused a significant reduction in the mosaic symptoms percentages, only, when used with a concentration of 200 ppm. Pre-inoculation treatment was more effective in reducing virus infectivity than post-inoculation treatment. [Journal of American Science 2010;6(9):5-13]. (ISSN: 1545-1003).