Aug 30, 2011

Basic info

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Cultivated maize

Food, feed and industrial raw material

Maize grows best with plenty of water, light and warmth, ideally at temperatures of 20 - 24ºC. It only really finds conditions like this in its tropical homeland. And yet maize cultivation has been able to penetrate further and further into the climatically unfavourable northern latitudes as more and more effective varieties adapted to specific climatic conditions are developed – varieties that are able to withstand cool spring weather, ripen earlier, are stable, can protect themselves against pests and still produce higher yields.

Maize: metre-high grass

Maize is an annual grass that grows up to five centimetres thick and seven metres high. In Germany the average height ranges from 1.7 to 2.5 metres.

Maize is a monoecious plant i.e. separate male and female flowers are found on one plant. The branched male inflorescences are at the top of the plant and supply the pollen; the female inflorescences are found on the side of the stem; they are encased in paper-like leaves or husks and produce long, sticky silks which catch the pollen. The infructescences, or maize cobs, develop from the female inflorescences.

Maize is wind pollinated. Since the flowers of the male panicles appear two to four days before the silks, cross-fertilisation takes place in around 90% of cases. After fertilisation the silks dry up and kernels begin to form. Maize has no native “wild” related species in Europe with which to hybridise, so it has no feral tendency.

Maize plants make little demand on the soil. They need plenty of water, but they are also good at exploiting water and carbon dioxide and produce a lot of biomass in relation to water consumption.

Maize has been cultivated for thousands of years and more than 3000 varieties have come about as a result of these endeavours. A few main varieties have evolved which can be distinguished by the character of the kernels. Dent maize or flint and dent maize hybrids are the most significant in commercial terms today. They are used mainly as animal feed, but also as a raw material for industrial products. Sweet corn is used as a primary foodstuff. It originated through a mutation, as did flour corn or soft maize, which for centuries formed the main foodstuff in South and Middle America where today many different local varieties are still grown.

Hybrid maize breeding

Hybrid maize varieties were first bred in the USA around 1910. Two different things were discovered: When self-fertilisation takes place in the maize plants, the resulting progeny are lacking in vigour and do not grow as well. However if these in-bred lines are crossed, the ensuing progeny grow particularly well and produce high grain yields (heterosis effect).This discovery revolutionised breeding practice and resulted in vast increases in yields and in maize cultivation throughout the world.

The seed for hybrid maize must be replaced each year i.e. bought in. If the harvested kernels are sown, less productive plants are produced again.

Cultivation and distribution

The area under maize cultivation in Germany increased enormously between 1960 and 1990, in particular because of the successes in breeding hybrid maize. In the last few years, there has been a new boom due to maize cultivation for energy generation. In 2010 maize is being grown on 2.3 million hectares; of this approximately 1.8 hectares is silage maize and 0.5 hectares grain maize. Since 1960 until today, the average yield of silage maize has doubled and that of grain maize tripled.

Today maize is grown mainly as animal feed, and maize for human consumption is generally only of secondary importance. For animal feed, the whole plant is used, rather than just the kernels and cobs. When maize is grown for silage, the whole plant is harvested before the kernels are even ripe, then chopped up and turned into silage – by fermenting the preserved green forage.

In Europe the main foodstuffs made directly from maize are popcorn and cornflakes, a small quantity of sweet corn as a vegetable and corn starch (mondamin). Vitamin-rich maize germ oil is made from the maize germ.

Although the potato is still the main source of starch in Germany, the importance of maize for the starch industry is growing steadily. The starch produced in maize kernels is now found in more than 500 everyday products. It is a carrier and a thickening agent, an adhesive and a coating compound, when converted to syrup it becomes a sugar substitute with preservative and stabilising properties. Around half of the maize starch is processed in the food industry, whilst the remaining half is used as a renewable raw material in the paper and packaging industry, in textile manufacturing, for chemicals, pharmaceuticals and many other applications.

In the past few years maize has increasingly been cultivated for energy generation. In 2009 the maize cultivation area for the biogas production in Germany amounted more than 300.000 hectare.