Wheat
"Wheat is a generic term for several cereals belonging to the genus Triticum. These are annual plants in the grass family (Poaceae), cultivated in a large number of countries. The word "wheat" also refers to the "grain" (caryopsis) produced by these plants.
Types and diversity of wheat
From an economic point of view, the two most important types of wheat today are hulled wheat :
Durum wheat (Triticum turgidum subsp. durum)
Mainly grown in Europe, North America and the Middle East. It is widely used in the Mediterranean region (Italy, Maghreb countries). Durum wheat, which is very rich in gluten, is used to produce semolina and pasta. Nearly 150 varieties are listed in the French Official Catalogue of species and varieties created by 10 breeding companies, and nearly 530 in the European Catalogue.
Some durum wheat varieties grown in France: Acalou, Actisur, Akenaton, Alexis, Anvergur, Argelès, Augur, Byblos, Chistera, Cordeiro, Duetto, Floridou, Joyau, Luminur, Pescadou, Pharaon, Sachem, Tablur, etc.
Common wheat(Triticum æstivum)
By far the most important, it is grown mainly - but not exclusively - in mid-latitudes (for example in China, India, the United States, Russia, France, Canada and Germany). It is grown to make bread flour. Its grains are separated from their husks when threshed. Commonly known as soft wheat or simply wheat, this species has spread widely over the world and has become the most widely grown cereal, followed by rice and maize. There are countless varieties throughout the world. Modern breeding, begun at the end of the 19th century by Henry de Vilmorin, has focused on three criteria : resistance to disease and the vagaries of the weather, high protein content, particularly gluten for bread-making, and of course yield. One of the side-effects of this selection has been the virtual disappearance of bearded wheats : as the gene is recessive, new wheats resulting from crosses between bearded and naked wheats quickly lose this characteristic.
More than 780 varieties are listed in the Official Catalogue of Species and Varieties created by 20 breeding companies, and almost 2,400 are listed in the European Catalogue.
Some common wheat varieties grown in France :
- Winter : Adagio, Aligator, Apache, Inspiration, Iridium, Isengrain, Isidor, Lavoisier, Messager, Nirvana, PR22R20, Odysée, Oratorio, Pueblo, Renan (INRA variety appreciated in organic farming), Sobred, Solution, Starway, Syllon, Tentation, Trémie...
- Spring : Florence Aurore, Granary, Josselin, Triso, Tybalt...
- Hybrids : As de cœur, Atoupic, Hybred, Hycrop, Perceval, Vergain...
Growing wheat
Cropping systems have favoured various types of wheat :
- Winter wheat is sown in autumn. It is typical of Mediterranean and temperate regions.
- Spring wheat is sown in the spring and is found in countries with harsher winters. The main difference with winter wheat is that spring wheat has difficulty withstanding low temperatures. Spring wheat does not need vernalisation, and there is little or no tillering. It is thanks to spring wheat that Western Siberia and Canada have become major producers.
Sowing
Planting a wheat crop is very important, as it determines the development and growth of the plants. Successful planting depends on :
- the choice of variety suited to the local climate and soil
- the sowing date
- sowing density
- sowing depth
Choosing the variety
Farmers generally grow several varieties of wheat. This diversity allows them to spread out their work and limit the risks associated with the climate and various crop pests and diseases. The criteria for choice are therefore technical :
- yield : this criterion is less important for plots with low potential
- baking value : farmers sometimes have contracts imposing strict technological quality requirements
- earliness : depending on the local climate and work schedule
- crop resistance to cold, disease, lodging and sprouting
- climatic requirements (temperature sum requirements)
Sowing date
This depends on a number of factors :
- previous crop
- variety
- climatic conditions
- soil conditions
- strategies to overcome pathologies or weeds
- production system
- the farmer's availability
Winter wheat needs fairly long periods of cold to acquire the ability to flower : this is the vernalisation phenomenon. Early sowing before winter is therefore essential.
Sowing density
What matters is not the quantity of seed per hectare, but the number of spikes or plants per square metre. In other words, the number of plants to be planted.
It varies according to :
- the type of seed : conventional or hybrid
- climate
- soil type
- germination capacity
- sowing conditions
- sowing date
- losses at emergence and over winter
