Corn was first domesticated by native peoples in southern Mexico about 10,000 years ago. The first appearance of corn in the history of European agriculture coincides with the discovery of America, when Christopher Columbus, returning from his first voyage, mentioned this new cereal referred to by the indigenous people of the island of Cuba as “Mahiz”. Since its introduction in Spain in 1943, corn spread quickly to other European countries and then to Africa and Asia. Nowadays, corn is a staple food in many places.
Corn (Zea Mais) is belonging to the grass family. It is a species endowed with remarkable polymorphism especially as regards the shape and composition of the kernels. Based on this last aspect, cultivated corn can be divided into 7 groups: Zea mays indentata (dent corn); Zea mais indurata (flint corn); Zea mays amilacea (flour or soft corn); Zea mais saccharata (sweet corn); Zea mais everta (popcorn), Zea mais ceratina (waxy corn); Zea mais tunicata (pod corn). The dent corn type is by far the most cultivated in the world.
Corn is an annual plant, with a single, stout, erect and solid stem. The apex of the stem ends in the tassel, the male inflorescence; while the female inflorescence is an ear placed at the axil of the leaves. Corn, like that of all grasses, has a fasciculate root system and therefore quite superficial even if it can reach more than 2 meters deep.
The large narrow leaves have wavy margins and are spaced alternately on opposite sides of the stem. Corn grain is an indehiscent fruit called kernels.
The life cycle of the maize plant can be divided into three different, well-differentiated phases:
- Germination and rooting of seedlings: from germination up to 5-6 leaves. In this phase the seedling grows and develops thanks to the reserve substances contained in the seed.
- Vegetative growth: from 5-6 leaves up to the stem elongation and the emission of the tassel. In this phase it is extremely important to avoid water, nitrogen deficiencies and other environmental stresses that would compromise the yield.
- Flowering and ripening of the grain: it is the final phase of the cycle in which fertilization and the accumulation of reserve substances in the kernels takes place.
90% of corn production is concentrated in the northern hemisphere and largely between the 35th and 45th parallel, the further north the temperature is generally insufficient, the further south the water is the limiting factor. The optimum temperature for corn is between 24 and 30 ° C (75.2 – 86 °F). Temperatures above 32-33 ° C (89.6 – 91.4 °F) are always harmful and below 10 ° C (50 °F) the development of the plant stops.
Corn prefers medium-textured, deep, well-drained soils rich in organic matter. The sowing time varies from region to region but the factor that more than any other influences the choice of the sowing time is the temperature of the soil. In fact, corn does not germinate below 10 ° C (50 °F), it germinates slowly at 12 ° C (53.6 °F) while at 15 ° C (59 °F) germination is rapid, and the plant emerges from the ground in about 10 days.
Fertilization has the aim to satisfy the nutrient needs of the crop and avoid the impoverishment of soil fertility, without however causing harmful overloads of nutrients in the environment which would cause pollution and a unitary loss also at an economic level for the farmer.
Corn is notoriously a crop with a high production capacity and therefore with high needs for nutritional elements. The nutritional elements are largely contained in the soil but often in insufficient quantities for the needs of the crop or combined in compounds that are unavailable for the plant.
Nitrogen is the most important nutrient for the productive result of the crop, the plant’s N needs are increasing until pre-flowering which represents the most critical stage for this element. For phosphorus, the rate of absorption occurs almost in parallel with the growth of the plant, but the initial stages of development represent the most critical period. The absorption of potassium basically ends with the flowering of the plant or shortly after. The other essential chemical elements, including micronutrients, are normally present in the soil in sufficient quantities for the development and regular growth of the plant except for Zinc which must be supplied at sowing or during vegetative growth.
The crop also benefits from the application of products with a biostimulant action, based on beneficial microorganisms and vegetable protein hydrolysates. These products are able to stimulate the emergence and root development in the early stages of seedling development, to improve the availability of nutrients in the soil, to increase the yield from a quantitative and qualitative standpoint, to reduce the negative impact of climatic stresses and to increase the nutrient use efficiency (NUE). The application of biostimulants increases the environmental and economic sustainability of the production system.
