Root Development and Phosphorus Uptake by Tomato Plants under Controlled Soil Moisture Conditions

Abstract

AbstractThe effect of soil moisture tension upon root growth and phosphorus uptake by tomato plants was studied using a split‐root technique. Root systems were developed in soil maintained at three different moisture levels—one well below PWP, another slightly below PWP, and a third within the “available” range. Root growth was very restricted at the lowest level of soil moisture—attaining a maximum length of 20 mm. At the level slightly below PWP, roots grew to a length of 90 mm, with substantial secondary root development. Maximum growth was attained at the moisture level maintained above PWP. At this level roots reached a length of 150 mm and exhibited extensive secondary branching.Phosphorus uptake was measured by use of radioactive P. At all three moisture levels phosphorus was taken up by the plants. A significant increase in uptake accompanied each increase in soil moisture.Moisture was transferred through the plant root system from zones of low tension to zones of high tension within the soil.