Wheat: Origin, Morphology and Economic Importance

Commonly called Wheat or Gehun is a cereal crop grown worldwide. Yes, we are talking about the star of the Poaceae family, Triticum aestivum. Let’s throw some light on Wheat’s Origin, Morphology and Economic Importance. Wheat is a monocot plant.

Part Used:

Grains, whole plant for fodder

Chromosome Number:

6n= 42

Genome:

AABBDD

Origin of Wheat

Wheat cultivation started in prehistoric times. As per De Candolle, it began in Mesopotamia. Even before its cultivation practice, it originated in the Levant region (Egypt, Greece).

Evidence from the village of Jarmo (Eastern Iraq) suggests Wheat cultivation. Subsequently and gradually the magic of wheat cultivation spread to central as well as north-eastern Europe in 6750B.C.-7500B.C. which was followed by the spread to the whole of Asia.

5000-year-old grains have been recovered from Mohanjodaro which is now in Pakistan but earlier was a part of India. Some of the studies from America also indicate its origin is from Syria and Palestine. Summing up with Nikolai Vavilov who examined 31,000 samples of Wheat plants. He reports that for soft-Wheat, the origin centre is South-Western Asia, moreover for hard Wheat the centre is the Mediterranean region.

Morphology of Wheat

The plant is annual with a height of 2.5-5ft.

Stem

The stem of wheat is also called culm which is cylindrical in nature. It is divided into solid nodes and hollow internodes. Talking a little more about the internodes, on the lower side of the shoot, the internodes are shorter while on the upper side of the shoot, the internodes are longer. Along with primary shoot, secondary shoots are also found which arise particularly from the underground axillary buds. Furthermore, the axillary buds on the underground portions of the secondary shoots give rise to tertiary shoots. The underground buds of these tertiary shoots in turn repeat the same growth pattern. This pattern of shoot growth is called tillering.

Roots

The plant bears two types of roots- Seminal or Primary roots and Coronal or Secondary roots. The seminal type of roots are 3-6 in number and are seen to arise from the embryo. Additionally, secondary roots are adventitious and are seen to arise from the lower nodes.

Leaves

Leaves are alternately present on the culm. Two auricles or special appendages are present on the base of the leaf. Talking about the leaf sheath, it forms the basal part of the leaf which has the role to encircle the stem. The leaf lamina is linear to lanceolate. There is also the presence of a leaf ligule at the junction of leaf sheath and lamina. The membranous ligule has particularly fringed margins and hairy outgrowths.

Inflorescence

The inflorescence is a distichous spike and is terminal in position. Spike is further composed of spikelets, the rachis is zig-zag. Spikelets are seen to be enclosed particularly in glumes and are alternatively present. Spikelets are seen to be born on the rachilla (a central axis). One to five florets are borne on the spikelets in an alternate fashion.

Talking about the florets, each floret is seen to be enclosed in an outer layer called lemma and an inner membranous layer called palea. 3 stamens are present in each floret. Moreover, one pistil is seen with two feathery stigmas.

Fruit

All things considered, the fruit of this plant is a one-seeded caryopsis where testa and pericarp are fused to form a husk. Pericarp can be of different colours depending on the variety (white, amber, red, or purple).
In general, the kernel (grain) has dorsal and ventral sides with a tuft of hair on tip of the grain. The dorsal side is seen to be smooth and convex. This side is slightly wrinkled at the base which indicates the location of the embryo. The ventral side has a particular crease (groove).

Image Source: https://etc.usf.edu/

Anatomy of Wheat Grain

The outermost layer of the Wheat grain is the fruit wall or pericarp made up of epidermis, hypodermis, cross cells and tube cells. Testa also called the seed coat is fused with the tube cells and cross cells of the pericarp on one side and the nucellar epidermis on the other side. The nucellar layer is particularly compressed and followed by the endosperm.

Nextly, the outermost layer of the endosperm is called the Aleurone layer, which is rich in components like minerals, niacin, vitamin B-complex, and high protein content. It is particularly devoid of gluten and starch. Surprisingly, the rest portions of the endosperm are rich in starch.  The cotyledon is called the scutellum. The plumule remains protected by a sheath called coleoptile whereas the radicle is enclosed in a sheath named coleorhiza. To conclude, the kernel is well developed and has 9-10% bran coat (which includes pericarp, testa, nucellar layer),3-4% aleurone layer, 2.5% germ (embryo), and 82% starchy endosperm.

Image Source: www.researchgate.net

Cultivation of Wheat

N.I. Vavilov determined 14 species of Wheat which were further grouped into 3 groups based on ploidy particularly- Diploid or einkorn wheat, Tetraploid wheat, and Hexaploid wheat.
It sounds unimaginable but the world’s Wheat production is about 350 million tonnes. Moreover, India is specifically the fifth producer of wheat in the world. However, Wheat is a temperate crop and grows well at 10-25 centigrade and an annual rainfall of 35-65cm is considered ideal. Another key point is that heavy loamy soil is the perfect soil type for the plant and fertilizers like NPK and Ca specifically have proved to be effective for good growth.

Economic importance

The economic benefits of Wheat are discussed and summarized in the following points:

1. Flour for making chapatis, flatbread, etc. It has become a source of staple food over time.

2. Secondly, refined flour commonly called maida is obtained from Triticum durum. Maida is further used in making macaroni, biscuits, etc
3. Wheat flakes are a cereal food.
4. Wheat starch is useful for finishing clothes in laundries.
5. Seeds are used in the production of alcoholic beverages specifically.
6. Semolina or Sooji is flour from wheat with large-sized particles. It is useful particularly in sweets.
7. Fresh straw is used as fodder to feed livestock.
8. Straw is used in papermaking and making building boards.
9. Green leaves of young plants have proved to cure cancer and reduce the side effects of chemotherapy. This is often referred to as wheatgrass.
10. Dry straw is used in making packing materials and mattresses.

11. Porridge is made from specialized roasted or unroasted shredded grains (hard Wheat) which is undoubtedly the best breakfast for a lot of people.

To summarize, this was all about the origin, morphology, and economic importance of Wheat, stay tuned for more botanical information on Wheat.

Thank you for reading.

Team MBD

For more on Botany: – My Biology Dictionary Gymnosperms vs Angiosperms

International Wheat Genome Sequencing Consortium: Home – IWGSC (wheatgenome.org)