Effect of viral infection on arbuscular mycorrhizal colonization in weeds

The present study reports the effect of viral infection on arbuscular mycorrhizal colonization in three weed species namely Ageratum conyzoides L., Croton sparsiflorus Morong and Malva parviflora L. Percentage of mycelial, arbuscular and vesicular colonization was recorded on the bases of presence or absence of theses tructures in twenty 1 cm root pieces. Extent of mycorrhizal colonization was recorded as cm/100 cm of root length. Arbuscular and vesicular infections were quantified by counting these structures per cm of root length.Mycorrhizal infestation was invariably absent in healthy plants of all the three test weed species. Moderately diseased plants of all the three weed species exhibited mycorrhizal colonization. In M. parviflora mycorrhizalcolonization and especially the number of vesicles was increased with increase in disease severity. However, in rest of the test weeds, the plants showing severe viral infections did not harbour any mycorrhizal colonization.