Maize: Hybrid and genetic modification


In 1716, Cotton Mather described maize which Americans call corn and pumpkins which are also known as squash as hybrid plants. On longer evolutionary time scales, hybridisation can lead to local adaption through introgression or reverse cross-breeding.

Maize, which falls in the grass family, was first domesticated by indigenous people in Balsas, the River Valley of south-central Mexico, about 10,000 years ago. The naturally-propagating ancestor of maize is teosinte and still grows wildly in Mexico.

The oldest surviving maize types are found in the Mexican highlands where it diversified before moving to the lowlands. Early maize plants were short with one cob (also called ear). Centuries of artificial selection of preferred varieties by the indigenous people resulted in maize plants capable of growing several cobs per plant, and much longer. This can't rule out continuous unpreventable pollination from teosinte over time.

The Spanish settlers came to love maize and their explorers and traders carried it back to Europe and introduced it to other countries.

Maize could adapt to different environments so it grew in many countries. It went to Italy, Portugal and West Africa. It was more preferred to wheat and barley as it gave more harvest on less land cultivated.

Before the British came to Kenya the Portuguese had introduced maize to the coast, where the Swahili grew and traded in it. The rest of Kenya relied on sorghum, cassava and millet for flour. Up to 1920 maize was grown in Kenya by settlers for export. Kenyans had not adopted it as a source of starch.

Farmers discovered that when yellow and white maize were grown in close proximity and cross-pollinated, the grains of the resultant cobs were mixed in colour, rendering it unsuitable for export.

By 1925, many Kenyans had gone to work in settlers farms and they were given maize as food ratio to grind at a nearby hammer-mill. This is how Kenyans began to adopt maize as staple food. In 1935, the colonial LEGCO passed the Native Produce Ordinance which was to give settler famers advantage over Kenyans who had taken up maize cultivation in full swing.

Hybrid seeds were cross pollinated to give another hybrid variety. The main disadvantage to growing hybrid maize was that uniform appearance came with a dangerous genetic uniformity. The more effort farmers put into making sure the plants all looked the same, the more genetically alike they became. This increased susceptibility to disease.

Hybrid maize is different from Genetically Modified (GMO) Maize. Changing plants and animals through traditional breeding takes a long time and it is difficult to make specific changes. Genetic engineering was brought in to enable specific changes over shorter period to be made. GM has made food crops beautiful and pleasing to the eye, while making the crops easier for farmers to cultivate.

The first genetic modified maize was grown in 1996. This is the modification of DNA using physical or bacterial genetic engineering methods. The aim is to introduce a new trait which does not occur naturally. These traits include, resistance to adverse weather conditions, certain pests, diseases, durability, resistance to chemicals or improving the nutrient content of the crop.

To produce a GMO plant, scientists identify what trait they want in the plant. They then look for an organism that already has that trait within its genes.

They identified a gene in a soil bacterium called Bt which produces natural insecticide. They identify that gene and copy it and insert it into the maize gene and the Bt Maize will grow resistant to insects.

With effects of climate change affecting traditional farming methods, genetic engineering is presenting man with a dilemma. The need to feed bulging population against ethical and safety considerations.

Want to get latest farming tips and videos?
Join Us