Growth and Specific Nodule Activity of Soybean during Application and Recovery of a Leaf Moisture Stress

Soybean plants growing at day/night temperatures of 30/18, 26/18, and 22/18 C were subjected to a single drying and recovery cycle during an 18- to 19-day period in the early to midpod development stage. Leaf total electrochemical water potential was reduced to about −24 bars during the 4-day drying cycle at all temperatures, but recovered to control levels upon rewatering. The changes in dry matter accumulation in whole plants and plant parts, specific activity of nodules as measured by acetylene reduction, and levels of adenosine phosphates in nodules were measured periodically during stress and recovery.