How Do the Roots of the Apple Tree Function?

Among many other things, the roots of an apple tree function to support its fruit development. In the spring, the apple tree's roots grow rapidly in search of nutrients and water. They also create the tree's leaves and flowers. In the summer, however, the roots cease to grow and focus on supplying water and nutrients to the tree.

Feeder roots

Apple trees have feeder roots that can grow as long as 12 feet. These roots also produce small branches that spread fruit and shade the ground. The roots are often deep, but will not damage the lawn infrastructure. These roots are usually not visible to the naked eye, and are a sign of a healthy tree.

The feeder roots will die off during winter, but the fibrous ones will grow back. These roots do not go dormant; they mine for nutrients for the next season. They also contribute to the stability of an apple tree's anchorage.

Taproot

The regenerative ability of a tree's roots is dependent on the size and shape of its taproot. In general, the more deeply seated the taproot, the more effective it is at anchoring the tree. However, it is not the only factor determining the anchorage capability of a tree. Other factors such as root architecture and the type of soil are also important.

The apple tree taproot system is similar to the taproot of a carrot. It is a mass of lateral fibrous roots that extends two to three times the width of the tree's canopy. During times of drought, the taproot can reach deep moisture stores. The rootstock of the apple tree is an important factor in determining the size and fruiting rate of the tree. Different rootstocks have different effects on the size of the tree and the speed of its root mass.

Lateral roots

The apple tree has a complex taproot system that resembles that of a carrot. These lateral fibrous roots extend about twice the width of the tree's canopy and regulate its spread by adjusting to the conditions in which the plant grows. These roots also produce fine feeder roots that feed on nearby surfaces, such as soil, and are capable of reaching deep moisture stores during periods of drought. The size of the mature tree depends on the rootstock, which affects its growth rate and fruiting.

Fine roots originate at variable distances from the apical meristem and grow through the cortex to form complex lateral branches. The lateral roots of a tree respond to changes in water and nutrient availability by branching out. The distal tips of these roots are the primary sites where mycorrhizas infect the tree.

Columnar growth habit

A natural apple tree mutant exhibiting a columnar growth habit has recently been identified, and this discovery provides new insights into how the roots of the fruiting tree develop and grow. The columnar habit is not a common phenotype among apple trees, and it is not known which gene is responsible. It is possible to detect the habit at a very early stage, but such evaluation is not reliable. It may take two or three years for a root to become fully mature.

Apple trees with this growth habit display thick, upright stems with short internodes. They have short lateral branches and fruit spurs, and their axillary buds develop into long side shoots with a narrow crotch angle. When the central leader is damaged, the side shoots develop in a columnar fashion and can reach 50 centimeters in length.