Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2002
Publication Date: 8/1/2003
Citation: Prior, S.A., Rogers, H.H., Mullins, G.L., and Runion, G.B. 2003. The Effects of Elevated Atmospheric CO2 and soil P placement on cotton root deployment. Plant and Soil 255 (1):179-187. Also published as a bookchapter: In Abe, J. (ed.). Roots: The Dynamic Interface Between Plants and the Earth. Development in Plant and Soil Sciences Volume 101. pp. 179-187. Kluwer Academic Publishers, Norwell, MA. Interpretive Summary: Increases in atmospheric CO2 can enhance root distribution which may help crops gather needed resources such as water and nutrients. Our goal was to examine the effects of high CO2 on cotton growth as affected by adding the same amount of P to different percentages of the soil volume. Shoot and total root growth was increased by extra CO2 but root growth in the P-fertilized soil fraction was similar under both CO2 levels. Ambient grown cotton was more dependent on P placement than cotton grown in high CO2. Thus, management strategies that use band application of P may be more flexible under elevated CO2.
Technical Abstract: Root proliferation into nutrient rich zones is an important mechanism in the exploitation of soil nutrients by plants. No studies have examined atmospheric CO2 effects on cotton (Gossypium hirsutum L.) root distribution as affected by localized phosphorus (P). Cotton plants were grown in a Troup sand (loamy, siliceous Grossarenic Paleudalts) using 17.2 liter containers placed in open top field chambers (OTC) under ambient (360 ppm) or enriched (720 ppm) atmospheric CO2 concentrations for 40 days. Equivalent amounts of P were added (150 mg P per kg of soil) to 100, 50, 25, 12.5, and 6.25 % of the soil volume; control containers with no added P were also included. Under extremely low P (controls), cotton was unresponsive to CO2 enrichment. In treatments with both fertilized and unfertilized soil volumes, root proliferation was greater in the unfertilized soil under elevated CO2 conditions. Stimulation of root growth occurred in the P-fertilized soil fraction; the pattern of stimulation was similar under both CO2 levels. Under ambient CO2, cotton plant response was positive (shoot mass, and total root mass and length) when soil P was confined to relatively small proportions of the soil volume (6.25 and 12.5 %). However, elevated CO2 grown plants tended to respond to P regardless of its distribution.