Principles for selecting the best Wheat Variety
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How to select the best wheat variety – Guide for wheat variety selection
The selection of the most appropriate variety for your specific field is one of the critical factors affecting wheat cultivation’s success.
For the past 9.000 years, farmers and scientists have been trying to create, monitor, test and select new, improved wheat varieties that fit the standards of modern needs, cultivation techniques, and market demands. Up to the 15th century, most wheat varieties were landraces. A landrace is a population of different wheat genotypes cultivated for a long time (e.g., centuries) in a region and has been highly adaptive in that specific conditions. Throughout the years, people selected the best-performed individuals (=genotype) and used them as varieties or in crosses to obtain improved offspring and hybrids. Some of the essential traits for the wheat domestication were (Peng et al., 2011):
- The loss of spike shattering (fewer seed losses due to early seed dispersal)
- The easiest separation of the seeds from the glumes (naked varieties)
- The loss of seed dormancy
- The change in plant architecture (less leafy-bushier, shorter plants), ear and kernel size
- The protein content
One of the first known varieties is the Squareheads Master, which was developed in the 1860s. It was shorter, with stiffer straw, and had a higher yield than its ancestors (1). However, most modern wheat varieties were developed during the “Green Revolution” around the 1950-60s as an answer to the increased global food demand. This era is characterized by the introduction of dwarfing genes from the Japanese variety ‘Norin 10’, making wheat varieties shorter. Stems of shorter height could withstand ears of higher weight without lodging, enabling a spectacular increase in wheat yield (Hedden, 2003). These genes are still present in more than 70% of modern wheat cultivars available in the market. The new varieties of the “Green Revolution” had also a higher Nitrogen demand and Use Efficiency, increasing the need for crop inputs (fertilizers) to achieve higher yields.
While yield was the main focus trait during the previous century, nowadays, breeders aim to improve traits linked to plant adaptability-resilience, resistance to abiotic (environmental) and biotic (pests and disease) stresses, and of course grain quality.
The thousand commercial wheat varieties (around 100,000) available are classified into different wheat classes based on their:
- Planting date (Winter-Spring)? 80% of the world’s wheat is winter wheat
- Grain Hardness (Hard, Soft, Durum) ?This refers to the resistance of the grain to milling (grind into flour) and reflects the quantity and composition of grain wheat protein (Khan, 2016). The different types of wheat, based on the grain hardness and protein quantity, are suitable for producing specific food products (Peña, 2002).
- Grain Quality (4 groups) ? It is determined by the variety, but the environment also affects it.
- Flour class (All-purpose, bread, self-rising, cake, semolina, and durum flour)
Since a farmer cannot test all existing varieties to decide which is the best, he/she can base the decision on other data available in combination with personal experience and the advice of a local licensed agronomist.
Factors and characteristics to consider for choosing the most appropriate variety of wheat.
Some of the key characteristics a farmer should take into consideration when selecting a wheat variety are:
→ The Yield Potential
→ Ability of the Variety to adapt to your local area: It is necessary to select varieties that can reach their yield potential in the local environmental-soil condition of the area the farmer wants to cultivate. A high-yielding wheat variety adapted to some specific conditions does not mean that it will be the best choice in every part of the world. To ensure that the variety has a steadily good performance in the local conditions, the farmer needs to have yield data of multiple season trials in the area of interest. There are varieties with broad adaptability. In this case, there is a higher chance the variety will give a yield closer to its potential in many different areas.
→ The Production System and the available applied management techniques: This could refer to the use of irrigation or the lack of it, the cultivation of the crop conventionally or with less (or no) inputs as well as the purpose of the crop (for grazing, feed, food production). The production system, the available inputs, and the crop’s yield potential are linked. For example, a high-yielding crop may need more fertilizers to reach its yield potential.
→ The sowing period and the life cycle length of the crop: Wheat varieties are classified as winter and spring based on the time period they are sown and grow. The farmer should also take into account the life cycle length of the variety. A wheat crop that has a shorter life cycle can “escape” adverse conditions like early heat waves (for winter wheat) and frosts (for spring wheat). On the contrary, in areas where the conditions are favorable for a longer period, the farmer may choose a variety with a more extended life cycle and perhaps higher yield potential.
→ The tolerance to abiotic factors: The farmer should detect the major limiting factor in his/her field and/or area and choose a variety that can cope with it while retaining its good productivity. This is especially important when the farmer does not have the means to control the abiotic stress effectively. For example, a variety with high drought tolerance is the best choice in areas where the rainfalls are insufficient, and the farmer cannot apply irrigation. Finally, the straw strength to lodging may be essential in areas with strong winds, especially during later developmental stages (closer to grain filling).
→ The resistance to Diseases and Pests: Farmers need to know which are the main “enemies” of the crop in the region and select a variety that has good tolerance or is resistant to them. Resistant varieties are an excellent control method for crop pests and diseases, reducing the need-amount of the chemical control needed (fewer inputs). Moreover, in some cases, due to reducing the available and certified active compounds for pest-disease control, genetic resistance is usually the farmer’s only effective option. However, the best results are often obtained by integrated management measures (using precautionary-preventing measures and resistant varieties). Many commercial varieties carry a good resistance to brown and yellow rust, fusarium ear blight, mildew, and eyespot.
→ Grain quality: The standards differ depending on the end product and grain use (human consumption or not). For example, wheat grains intended for milling and baking should have around 14.4% (12% mb) protein content, while for the production of cakes and pastries, the value should be lower, in the 7–11% range (13.5% mb) (Khan, 2016). On the other hand, durum wheat grains need to have 13.5% or higher to produce pasta with 12.5% protein levels (7). Nowadays, milling and baking companies have created detailed lists with quality requirements. In some cases, they publish a list of “preferred wheat varieties” that produce grains that satisfy the quality standards (2).
As mentioned above, some parameters and characteristics may affect the expression of others. As a result, farmers should follow a holistic approach and take everything into account before choosing a variety. For example, for early sowing (in winter wheat), it would be best to select a frost-resistant variety with high resistance to fungal diseases that has strong stems (straws) and slow development. To help the farmers make an informed decision, some tools (3) and varieties lists are published by local authorities (4, 5, 6).
Tip: Avoid monoculture with only one variety
Using only a single variety (=genotype) in a large area is usually the source of many problems. To reduce the risk of yield losses due to abiotic and biotic stresses, the farmer could scutter the danger and cultivate more than one wheat variety with a difference in one or some characteristics of interest (disease resistant, drought resistance, maturity time, etc.). This is called “Variety Complementation”. For example, suppose there is a risk of rust infection in a specific area. In that case, a farmer can select to cultivate both a high-yielding variety (that is more susceptible to the fungus) and a highly resistant cultivar (that may have less yielding potential). The change of the variety cultivated could also be performed from year to year.
- Variety selection tool for cereals and oilseeds | AHDB
Hedden, P. (2003). The genes of the Green Revolution. TRENDS in Genetics, 19(1), 5-9.
Khan, K. (2016). Wheat: chemistry and technology. Elsevier.
Peña, R. J. (2002). Bread wheat improvement and production. Food and Agriculture Organization of the United Nations, 483-542.
Peng, J. H., Sun, D., & Nevo, E. (2011). Domestication evolution, genetics and genomics in wheat. Molecular Breeding, 28(3), 281-301.
Principles for selecting the best Wheat Variety