Making water stress treatments in pot experiments: An illustrated step-by-step guide v1

This protocol is a step-by-step guide on how to make water stress treatments in pot experiments. Water stress treatments are useful for investigating how plants survive under drought conditions. This protocol demonstrates how you can keep plants severely water stressed, moderately water stressed and well-watered. Note that water stress is sometimes also referred to as soil moisture stress or simply as moisture stress. The terms will be used interchangeably in this protocol. Water stress treatments are made by reducing a soils moisture content and by maintaining the moisture content at this new low level for a period of time. Changes in soil moisture are achieved by reducing or increasing a soils moisture content to levels close to or way below its field capacity (water holding capacity). Field capacity is the maximum amount of water that a soil retains after the excess water it had gained from an irrigation or rainfall has completely drained and its percolation seized. Note that moisture content at field capacity is not the same as that held under saturated soil moisture conditions. At field capacity the large soil pores are filled with both air and water, while the smaller pores are still full of water. While at saturation all pores are filled with water. Plants need both air and water in soil pores for them to grow well making field capacity an ideal soil moisture level. There are many methods for creating water stress treatments. The method described in this protocol is however suitable for all situations.