International audienceWheat is a major source of protein for human food, a critical issue at a time when mankind is growing by 77 million people per year. Wheat was domesticated approximately 10,000 years ago and has been systematically bred for about 200 years. However, this breeding selection has been done using only aerial plant parts. Indeed, wheat roots, the hidden half of plant, were not considered in breeding programs due to the lack of an appropriate method. Here, we evaluated roots of 18 wheat populations. The root system size was measured by its electrical capacitance directly in field. The plants in third and fourth generations were evaluated during shooting and heading. Then plants were selected for large and small root system. In dry conditions, progeny of plants with large and small root system had yields of 17.1 and 10.9 g per plant in the third generation and 18.5 and 10.0 g per plant in the fourth generation. Our results show that the progeny of the plants selected for large roots have larger roots than their parents, also in next generation. Similarly, the progeny of small root plants have smaller roots. The selection process showed a greater response for larger root system size. This response can be evolutionarily advantageous and make selection easier than, for example, selection for grain yield. Our unique method enables accurate, repeated evaluation and harvest of selected plants. Selection for higher wheat root system size can be easily used to breed for drought tolerance and higher efficiency of water and fertilizer use