What is water stress ?

When water availability—or soil tension—attains a certain threshold, plants experience water stress and react by slowing or stopping their growth. This is a normal plant reaction to an insufficiency of water in the soil; the plant is simply taking a drastic reaction to survive. In agricultural production, however, this survival reflex can be costly if it occurs regularly throughout the growing season. Slowed or stopped growth can reduce crop yield. It may be desirable to induce stress in certain situations to force the plant to react, but if this stress is not properly measured and monitored, it is difficult to attain the right level of stress at just the right moment.