Which Part of the Sweet Potato Plant Absorbs Water & Mineral Salts from the Soil?

The Root System

• Sweet potatos absorb water and nutrients from the soil via small, fibrous roots. They have a vining growth habit, sending roots into the soil in the places where ground contact occurs. These roots anchor the plant to the soil, as well as provide nutrients. Part of the root system grows through the soil and absorb nutrients directly from the earth, and other roots swell up to become storage roots. What is commonly called the sweet potato is actually the storage root -- the part of the plant that serves as a repository for stored sugars in the form of starches, as well as other nutrients gathered by the root system.

Structure and Function

• On the cellular level, the part of the sweet potato root responsible for nutrient uptake consists of the epidermis, root hairs, epiblem, cortex, endodermis, pericycle and vascular tissue. The vascular tissue carries absorbed water and nutrients throughout the rest of the plant. Root hairs absorb these nutrients via osmosis and mass diffusion, and serve to increase the nutrient absorbing surface area of the plants root system. New root shoots grow in the pericycle, moving through the cortex as they grow and break into new areas of soil. The dermal tissues provide protection and structural integrity for the root system.

Role of Fungi and Bacteria

• Sweet Potato roots are aided in their uptake of water and minerals by certain beneficial microorganisms: Mycorrhizae and Rhizobium. Mycorrhizae are fungi that form symbiotic relationships with the root tissues of plants; enabling them to absorb and use nutrients they would not otherwise have access to. The bacterium uses the carbon waste produced by the plant to survive, and the plant gains access to an increased supply of soil nutrients. Rhizobium is a bacterium that forms nodules on the root system, aiding in the process of nitrogen fixation.

Soils

• Sweet potato roots require the proper soil to efficiently absorb water and nutrients, one that is sandy and well draining. Hard, clay soils inhibit root growth, resulting in misshapen, poorly growing plants. Soils with high moisture retention prevent roots from drying out, making the plant susceptible to root rot. Sweet potato root systems also require soils slightly on the acidic side, with a pH of 5.6 to 6.5. Root systems of plants in more neutral soils are more susceptible to disease.