Physiology and Development of Maize

Germination and emergence Germination triggered by the imbibition of the grain results in a mobilization of reserves and scutellum of the albumen and the development of radicle and seminal roots that appear secondary level node scutellaire. At the other end of the embryo develops gemmule the form of the coleoptile which pushes up and forms a plateau tillering. At this level form a first set of roots, stems and sometimes secondary and coleoptile penetrates soil and opens, releasing the first leaves. From this stage, the young corn plant becoming autotrophic.

Vegetative phase

However, the root system of maize is characterized by roots (called root surface), which collect water and nutrients to the plant in the most superficial layers of the soil. This imbalance in the extraction of mineral resources that the crop is very demanding in nitrogen fertilizer and water in proportion to the yield it provides, which poses serious environmental problems in temperate regions.

In temperate areas of the northern hemisphere, the corn is planted in April - May and blooms in July - August Grains reach maturity in October - November. Harvesting takes place when the ears have lost their green color. The entire plant can be harvested and ensiled before maturity of the grain (in September).

Natural resistance

Young corn plants accumulate a particular substance, the hydroxamic acid (2.4-dihydroxy-7-methoxy-2H-1.4-benzoxazin-2 (4H)-one or DIMBOA), which creates a natural resistance against a variety of enemies of the plant: insects, fungi and bacteria. We find this substance, DIMBOA, even among related species, including wheat. DIMBOA confers with the young corn plants resistant to the corn borer (family Crambidae). However, this resistance declines rapidly as the plant has passed the stage six sheets.

When maize is attacked by larvae of the caterpillar pests like the corn borer, it emits volatile molecules that attract predators of insect pest parasitoids such as Trichogramma.

Reproductive phase

Photosynthesis and yield potential

Maize and other tropical grasses (such as sugar cane or sorghum, for example), is part of the plant known as "C4" . These plants perform photosynthesis them more effectively than do the other plants (so-called "C3"). According to various studies the efficiency of photosynthesis (ie the transformation of light energy into organic matter) from corn is about 5 to 6% in the best conditions expérimementales . The practical performance depends on climatic conditions, sunshine and temperature (assuming that the nutrition of the plant - water, nitrogen, etc.. - Is not coercion), and leaf area index. This index is the ratio of leaf surface to the ground reflects the capacity of the plant to intercept light radiation and can routinely achieve five or six in the southwest of France, even ten to twelve. Therefore, maize is able to accumulate 600 kg of dry matter per hectare per day, which corresponds to a grain yield of 200 quintals . The record really known was established on a farm in Illinois (United States) with 235 q / ha.