by About 12,000 years ago, the Neolithic Revolution radically changed the economy, diet, and structure of the first human societies in the Middle East’s Fertile Crescent. With the beginning of grain cultivation – such as wheat and barley – and the domestication of animals, the first cities emerged in a new social context characterized by a productive economy. A study has now been published in the journal Trends in Plant Science and jointly managed by the University of Barcelona, the Center Agrotecnio and the University of Lleida, analyzes the evolution of the ears of wheat since the beginning of their cultivation by the inhabitants of ancient Mesopotamia – the cradle of agriculture in the world – between the Tigris and the Euphrates .
The authors of the study are Rut Sánchez-Bragado and Josep Lluís Araus-Ortega from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry Science and Engineering, and Gemma Molero from the International Maize and Wheat Improvement Center in Mexico, currently a researcher at KWS Seeds Inc.
A grain that changed human history
The cultivation of wheat – a grass that became a staple food – marked a turning point in the progress of human civilization. Today it is the world’s most important crop in terms of food security, but EU data warn that the effects of climate change are coming at a price could increase significantly and alter their production process in certain regions of the world.
During the wheat domestication process, the plant phenotype has undergone both rapid (within a few hundred years) and slow (thousands of years) changes, such as B. the weakening of the spindle, the increase in seed size and the reduction or disappearance of the awns. Above all, wheat varieties with and without awns are found all over the world, although the latter are common in regions with arid climates, especially in the last stages of cultivation in late spring, a condition typical of Mediterranean environments.
“It is important to conduct studies that show which wheat varieties are best adapted to different organic growing conditions, especially in the context of climate change. Looking back into the past can give us an idea of the development of wheat cultivation over the millennia since the advent of agriculture in ancient Mesopotamia,” says Rut Sánchez-Bragado, first author of the study, who received her PhD from UB.
“Awns are ear organs traditionally associated with the plant’s adaptation to drought,” says Josep Lluís Araus, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences in the Faculty of Biology.
“However, archaeological and historical records show that the wheat ear existed predominantly with awns more than ten millennia after wheat was domesticated. Farmers – probably in an undirected manner – opposed this organ,” points out Araus, one of the world’s most cited authors according to Clarivate Analytics’ Highly Cited Researchers (2022).
“The role of wheat awns in their performance remains controversial despite decades of study,” says researcher Gustavo A. Slafer, corresponding author of the study.
Ear awns: good for the plant?
Is the presence of awns on the ears beneficial for the plant and the harvest? Although there is no scientific consensus, “evidence suggests that under conditions where the plant does not suffer from water stress, the additional photosynthetic capacity of the awns does not compensate for other potential negative effects (reduced susceptibility to fungal diseases, limitation of the total number of large ones). wears an ear, etc.),” says Araus.
“In wetter climates, however, the awns store moisture and can promote the spread of diseases,” says Rut Sánchez-Bragado. “As the world population continues to grow, there is a need to study the role of awn spikes in the changing conditions of our climate to meet the global demand for a staple food like wheat.”
Under dry conditions, the ears – including the awns – have “better physiological properties than the leaves of plants to do more photosynthesis. Therefore, in dry conditions, the awns can still be beneficial or at most neutral to the plants,” concludes Professor Josep Lluís Araus.
