CWC Video 4 Script

Did you know that wheat is grown in 42 states in the US? The wheat plant is responsible for about 75% of all U.S. grain products. These products include pasta, noodles, cookies, and much more! All these foods are made from wheat flour. The wheat flour is milled from the wheat kernels but all parts of the wheat work together to make sure these kernels are ready for us to harvest, mill, and eat. 

Let’s learn more about the different parts of the wheat plant and their important role in the plant!

Roots 

Roots have four primary functions: 

To anchor the plant to the soil, absorb water and nutrients into the plant, store the plant’s food and sugars, and in some plants, help with vegetative reproduction.

A wheat plant typically has two types of roots: the seminal roots and the nodal roots. Let’s talk about the seminal roots first. About six of the primary roots are present in the seed. Once the seed germinates, the primary root bursts from the seed. Soon after, four or five lateral seminal roots emerge. These form the seminal root system, which may grow more than 3 feet in depth and support the plant until the nodal roots appear.

Like seminal roots, nodal roots initiate after germination but they emerge after some plant development. They are associated with tiller development and usually grow out when the fourth leaf emerges and tillering starts. Nodal roots are thicker than seminal roots and grow horizontally. 

Once the wheat is mature, the root system can extend between 3 and 6 feet or more depending on soil conditions. Most roots are in the top 30 cm of soil.

An important function of this system is to prevent the wheat from being blown over as the wheat grows taller and taller. In wheats that are too tall, the stem of the wheat can break because the roots securely anchors it in place but gravity pulls down on the top of the plant.

Stem 

The stem is the main stalk of a plant that develops buds and shoots and usually grows above the ground. The primary functions of the stem are to support the leaves, transport water and nutrients to the leaves, and to transport food and energy from the leaves to other parts of the plant, including the roots. 

Wheat in the field starts to extend its stems in the spring. The stem is still hidden inside the upper leaves which continue to grow before they sequentially unfurl. Along the stem, there are hard lumps, these are the nodes. Leaves are joined to the stem at a node. The internode are in between each nodes and these are the parts that grow to extend the stem. Nodes are sites of activity that allow the internodes to extend. 

The internodes at the base of the stem do not extend but the internodes higher up extend in sequence. Each one of these internodes grow a little longer than the previous one. The wheat will typically grow up to 4 feet.

Tillers 

Tillers are shoots that arise from the crown or base of the wheat. The process of producing these lateral branches or shoots is called tillering. The tillers form as the leaves emerge from the wheat plant. The tillers can produce their own leaves and roots. 

The number of tillers that grow are dependent on a number of factors including: plant population, planting date, and soil health. The tillers have to compete for light and nutrients so some of the tillers will die without producing a wheat ear. 

Tillers are associated with the potential yield. The number of tillers and how many of these survive through to harvest determines the number of ears at harvest. 

Leaves

Leaves are green, usually flat parts that grow from a stem or twig of a plant and function mainly in making food through photosynthesis. 

Photosynthesis is the process in which green plants produce simple carbohydrates by using carbon dioxide, hydrogen and a light source. The simple carbohydrates give the plant energy to grow and also can be stored in the seeds to help them become plants!

As we discussed earlier, the roots bring in nutrients and minerals into the plant and they are transported to the leaves via the stem. Once they reach the leaf, they are converted into usable products through photosynthesis. 

Leaf shape and size change with leaf position. The lowermost leaf on the main shoot has parallel sides within 1 cm of the tip so that the tip itself is blunt. The leaves above the first have more or less parallel sides for about two-thirds their length above which they taper to a sharp point. The last leaf produced from the stem, the flag leaf, becomes more narrow from about the lower third, giving the leaf an elongated ovate shape.

The flag leaf is the last leaf to emerge. Like all the other leaves, it produces food and energy. However, the flag leaf is responsible for around 75% of the effective leaf area that will produce the energy that will fill the grain and feed the head of the wheat. In general, the plant relies on its two topmost broad leaves to produce sucrose to fill the kernels.

The lower leaves will be responsible for providing energy for other plant functions. 

Head 

The head of the wheat is the part of the wheat plant that contains the kernels. It is also known as an ear or spike. The head will form at the top of the plant and usually contain 35-50 kernels. There are two main parts of the head: the awn and the kernel. Let's discover more about these parts!

Awn 

The awn is a slender, bristle-like attachment found at the tips of the head. They serve several functions and most of these functions improve carbohydrate production. They can produce photosynthates for the head, but they can not fully replace flag leaves if any damage were to occur to them. The awns can make a large contribution to plant energy in situations where the leaves of the plant begin to die prematurely, there’s a water shortage, high air temperature, or other environmental conditions that affect leaf photosynthesis. 

Kernel 

The kernels are the seeds and are harvested to make flour. Wheat kernels are also called ​wheat berries​ or grains. There are three main parts in a wheat kernel: the endosperm, bran and germ.

The endosperm is the largest part of the kernel and represents about 83% of the kernel weight. It contains most of the protein and carbohydrates. 

The second largest part is the bran, which represents around 14% of the weight. The bran is high in fiber and is milled in whole wheat flour. 

Finally, the germ is the smallest part and represents about 3% of the kernel weight. The germ is the high-fat sprouting part of the seed.

Conclusion

Now that we’ve covered information on the major parts of the wheat plant, you have a better understanding on how each part works together to produce a healthful food for us. From the roots, to the awn, all the structures serve a function in producing the kernels we use to make flour.