Cotton Root Water Uptake: Experimental Set-up and First Look at Data.

Cotton was grown in large column lysimeters.  The column profiles were split with the lower portion of diferent treatments receiving irrigation water of various salinities, while the upper part of the profiles were irrigated using good quality water.  The upper portion of the profile was allowed to dry after 40 days.  During this time the lower profile continued to be irrigated with saline waters.  After approximately 50 days of no irrigation, good quality water was reintroduced to the upper profile.  Drought stress induced roots in the lower portion of the profile to compensate for reduced water uptake in the upper profile.  The degree to which the roots in the lower profile compensated depended on the salinity of the water in the lower profile.  After irrigation water was administered to the upper profile, several hours to several days were needed for water uptake to resume to its pre-stress condition.  Once the stress was relieved, water uptake from the lower portion of the root zone was reduced as water uptake from the upper profile increased.