The availability of water marked the adaptation of local durum wheat varieties in the Mediterranean
- Durum wheat varieties in dry and wet areas use water differently before and after flowering, according to an IRTA study
The results will help to develop varieties adapted to the new environments that climate change will bring
Durum wheat varieties in the drier, warmer countries of the Mediterranean basin (Syria, Jordan, Lebanon, and Israel) are lower, flower earlier, have a longer grain filling period, and produce more and larger size spikes for unit area rather than varieties from wetter and colder areas. The grains of the durum wheat varieties in the colder areas, on the other hand, are heavier and fill faster. This is the main conclusion reached by a study by the Institute of Agri-Food Research and Technology (IRTA), which states that “the varieties in one area and the other have an unequal capacity to use the water available before and after flowering”, explains Dra. Conchita Royo, researcher in IRTA’s Sustainable Extensive Cultivation program. According to the researcher, the results of the study “will allow the selection and improvement of new wheat that will be better adapted to the dry and hot environments predicted by climate change models”.
For this study they have used a wide collection of traditional varieties of durum wheat from 21 countries in the Mediterranean basin which the same group created from seeds from various germplasm banks.
Using historical series of climate data from the major wheat cultivation areas in the Mediterranean basin, they first identified the eastern Mediterranean region as the warmest and driest due to its high temperatures, solar radiation, and potential evapotranspiration, and to the little rainfall and relative humidity.
Thanks to molecular markers, they identified the regions of the genome associated with certain agronomic characteristics. Thus, they observed that varieties adapted to the driest and warmest area use the water available in the soil before flowering to accumulate soluble carbohydrates which are subsequently mobilized towards the grain; varieties adapted to wetter and colder areas, on the other hand, make better use of the water available after flowering to fill the grain. The study also reveals that some molecular markers associated with these agronomic characteristics are found at different frequencies in the genome of varieties in both geographical areas. “This suggests that, in order for plants to survive in each environment, natural selection acted on traditional varieties by adjusting the values of each characteristic and the frequencies of the alleles associated with them,” says the IRTA researcher.
These findings are the result of several projects funded by the Ministry of Economic Affairs and Digital Transformation (MINECO), aimed at studying the characteristics of wheat that favor its adaptation to environments with different climates.
The domestication of wheat
Wheat was domesticated in the Fertile Crescent during the Neolithic Revolution, some 10,000 years ago. From there, the wheat was dispersed across the Mediterranean basin, reaching the Iberian Peninsula 3,000 years later. Natural selection meant that, once they arrived in a certain area, they gradually acquired adaptive advantages to the new environmental conditions through changes in their life cycle (phenology) and in the characters linked to greater grain production. The evolution of wheat during this long migration process and the selection made by humans with the beginning of agriculture, resulted in traditional varieties, also known as local varieties or landraces. These are varieties considered endemic to the area where they originated, to which they are very well adapted. That is why they are a unique material for the studies of adaptation of wheat to climate change.