Submitted to: Open Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2014
Publication Date: 4/1/2014
Publication URL: http://handle.nal.usda.gov/10113/59343
Citation: Benjamin, J.G., Nielsen, D.C., Vigil, M.F., Mikha, M.M., Calderon, F.J. 2014. Water deficit stress effects on corn (Zea mays, L.) root: shoot ratio. Open Journal of Soil Science 4:151-160.
Interpretive Summary: Soil physical conditions affect both root growth and shoot growth of plants. A study was conducted at the USDA-ARS Central Great Plains Research Station, Akron, CO to investigate the relative effects of restrictive soil conditions caused by low water content and high bulk density on root and shoot growth of corn. The study found that the Least Limiting Water Range (LLWR) was useful to indicate restrictive soil conditions. There was a linear decline in root biomass and shoot biomass as the days of growth with soil water contents outside LLWR increased. The relative decline of shoot biomass was greater than the relative decline in root biomass, leading an increase of root:shoot ratio as stress increased. Soil management techniques that improve the LLWR and maintain soil water contents within the LLWR during plant growth will minimize soil physical limitations on crop production.
Technical Abstract: A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations between Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. The criteria for determining restrictive soil conditions defined by the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.