Why cultivating drought-resistant plants disappoints: Soil physics may be the real bottleneck‎

Plants need water, light, and air to thrive. But when they transport water from the soil up to their leaves, they defy gravity. Scientists describe this astonishing phenomenon as "negative water potential," a form of negative tension that enables herbs, shrubs, and trees to draw water from the soil. Nevertheless, plants do not constantly extract water from the soil. For decades, researchers have sought to understand what limits a plant's water uptake.