Very shallow rooted (15-30 centimeter) crop is

A very shallow-rooted (15 - 30 centimeter) crop is onion.
Shallow-rooted crops have main root systems in the top 1 to 2 feet of soil. Examples are cabbage, cauliflower, lettuce, celery, sweet corn, onion, white potato and radish.
Onion plants have fibrous roots. Fibrous roots arise from the base of the stem leaves rather than from the radicle. They are bushy roots formed by several thin, hairy and moderately branched roots. Onion root tips containing meristematic cells are used for microscopic study of mitosis cell division stages.