Corn’s growth and development are complex processes and while one part of the corn’s plant is developing and growing, other part of the corn’s plant might be dying. There are nine stages of development of the plant, as noticeable in figure 1.
Figure 1, nine cycles of growth of corn, and water required in each of the stages to support the plant in its growth.
Growth of corn plant is usually divided into two stages: vegetative growth stage and reproductive development.
Vegetative growth stage is measured using the number of leaves method. The corn is put into a growth category by the number of leaves it currently has. Vegetative stages are labeled with the letter “V”, so if the corn plant is at the development, and it has seven leaves at a current stage of development, its current stage of development would be labeled as “V7”, look figure 1 above. Vegetative stages are labeled with letter “V” and the number represents the number of leaves the plant has at the current stage of development. When maize progresses until stage V4 or V5 some of the leaves might have fallen off because of the stem expansion and because the plant is aging. So, to determine the V stage, one should count the number of nodes from the bottom of the stem to the top, nodes being the places on the stem where there are currently leaves or where there was a leaf previously. When all the branches of the plant are fully emerged, corn reaches stage VT, or the final V-stage, as seen in figure 2.
Figure 2, VT stage; all branches are fully emerged on the corn.
Reproductive development stages are labeled with the letter “R” instead of “V”. As seen in figure 1, R1 stage of development is defined as the silk starts growing from the top of the corn plant. Rest of the R stages depend on the development of the kernels, or seeds in the ear of the corn. R stages begin when the tassel pollinates the ear. To be able to identify the next stages of corn development, husk should be removed. As soon as seeds are fertilized they begin developing. Seeds that are fertilized the first are on the base of the ear, and as seeds get fertilized, they fill the ear to its tip.
Seed of the Plant
Kernel or the seed of the corn plant consists of three main parts: the pericarp (also known as seed coat), the starchy endosperm, and the germ (embryo), look at figure 3. Pericarp part of the seed protects it before it is planted and after it has been planted against bacteria and fungi. Endosperm part of the seed provides enough energy for the plant to start growing and producing leaves. And lastly, the embryo part of the seed contains firstly developed parts in new seedling, consists of the point when the corn plant starts growing, which includes the first five to six leaves, and it also contains the initial root.
Figure 3, kernel of a corn labeled
The Corn Plant
Main parts of a corn plant are coleoptile, leaves, stalk, roots, ear and tassel. Other grain crops have two genders and are not separate, while corn plant has two separate genders, tassel and the ear. Corn is type of monoecious, and it is when both flowering structures are on the same plant.
Coleoptile is one of the main parts of the plant, as it protects four or five leaves rolled up inside each other, also called plumule. This occurs during germination. It is an important part of the plant as it pushes the plumule through the covering of the kernel and then through the surface. (figure 4)
Figure 4, coleoptile on the corn during germination.
Leaves on a corn plant consist of different parts, leaf blade, leaf midrib and leaf collar and sheath. They are produced on different sides of the corn and in a set order. Photosynthesis occurs on the leaf blade. Length of the leaf from the base to the tip is extended by leaf midrib. It provides the leaf with a structural support. Leaf blade and leaf sheath join on the inner surface of the leaf or collar. Sheath attaches the leaf to the stalk. (figure 5)
Figure 5, leaves of the corn
The main purpose of the stalk is to give structural support to the leaves for them to be able to attract sunlight. (figure 6)
Figure 6, corn stalk
The ear of the corn has cylindrically arranged group of flowers, each flower has an ovary that contains a silk. If the flower is fertilized successfully than it is able to produce a kernel. Usually there are around 700-1000 kernels arranged on the cob. (figure 7)
Figure 7, corn ears.
The male part of the corn plant is called the tassel. Corn plant has separate male and female flowers. The main purpose of the tassel is to produce pollen so it can fertilize the flower, or the female part of the corn plant (ear). Tassel usually produces 2 million to 5 million pollen grains. Also, corn is wind pollinated where wind carries pollen to the ear. (figure 8)
Figure 8, tassel of the corn.
In Serbia, corn is planted in around March or April, while it is harvested in around October or November. However for the rest of the world, it can be seen in the table below.
Table 1, planting, developing and harvesting seasons in the world regarding corn.
As noticed in the table, depending on the southern and northern hemisphere, corn has different seasons of planting. In northern hemisphere, Europe plants their seeds the soonest due to its warmer climate while Canada plants their seeds the latest, in May/June due to its colder climate. Regarding the southern hemisphere, corn is planted in the opposite seasons from northern hemisphere. While in south, they are planting their seeds, in north they are harvesting the corn seeds.
Source 1: Book, O’Keeffe, Kieran. Maize Growth & Development. Orange, N.S.W.: NSW Dept. of Primary Industries, 2009. Web.
Source 2:”How a Corn Plant Develops.” How a Corn Plant Grows. N.p., n.d. Web. 07 Feb. 2016.
Source 3: “Life Cycle of a Corn Plant.” YouTube. YouTube, n.d. Web. 07 Feb. 2016.
Figure 1: Colless, J. M. Maize Growing. Orange: NSW Agriculture, 1992. Print
Figure 2: “Kieran O’Keeffe.”Kieran O’Keeffe. N.p., n.d. Web. 01 Feb. 2016.
Figure 3: “Heat Stress On Late Grain-Filling In Corn.” IGrow. N.p., n.d. Web. 03 Feb. 2016.
Figure 4:”Coleoptile.” Coleoptile. N.P., n.d. Web. 04 Feb. 2016.
Figure 5: “Determining Corn Leaf Stages.” – Corny News Network (Purdue University). N.p., n.d. Web. 04 Feb. 2016.
Figure 6:”Corn Stalk.” Autodesk 123D. N.p., n.d. Web. 04 Feb. 2016.
Figure 7:”Corn – Ears.” N.p., n.d. Web. 04 Feb. 2016.
Figure 8: “Growing Sweet Corn – Alarm Clock Wars.” Alarm Clock Wars. N.p., 30 June 2015. Web. 04 Feb. 2016.
Table 1: “We Are the Answer Company.” Home. N.p., n.d. Web. 07 Feb. 2016.