The effect of soil volume and plant density on mycorrhizal infection and growth response was studied with onion. There was a significant negative correlation between percentage vesicular-arbuscular mycorrhizal infection and root density. The growth response due to mycorrhiza decreased when less soil was available for the plant. The root: shoot ratio decreased with increasing plant density in both mycorrhizal and non-mycorrhizal plants. Pot size did not affect the root: shoot ratio.
Growth response Mycorrhizal infection Onion Root density Soil volume VA mycorrhiza