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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #314274
Title: Elevated carbon dioxide and soil moisture on early growth response of soybean

Author
item MADEGOWDA, MADHU - Indian Institute Of Soil And Water Conservation (IISWC)
item Hatfield, Jerry

Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2015
Publication Date: 2/27/2015
Citation: Madegowda, M., Hatfield, J.L. 2015. Elevated carbon dioxide and soil moisture on early growth response of soybean. Agricultural Sciences. 6:263-278.

Interpretive Summary: Increasing concern over the potential effects of rising carbon dioxide levels in plants coupled with the increasing variation in precipitation have raised questions about the effects on crop plants and future productivity. An experiment was conducted on soybean growth under two carbon dioxide levels and three soil water levels to understand what the effect would be on the rate of growth and total amount of growth. These types of studies are necessary to provide an indication of the potential practices to offset the impact of climate change. Increasing carbon dioxide decreased the rate of growth and inadequate soil moisture further slowed the rate of development. The overall effect of increasing carbon dioxide is to increase plant size which offset the impacts of reduced water supply. Management of crops under future climates requires an understanding of the carbon dioxide and soil water interactions because both scenarios will occur. This information is of value to scientists and policymakers to more completely understand the potential impacts of a future climate on plant growth.

Technical Abstract: Interactions between elevated CO2 and soil water availability have the potential impact on crops and future food security of the world. The study was conducted to investigate vegetative growth response of soybean under two CO2 (380 and 800 µmol mol-1) with three soil moisture levels in controlled environment. Slow growth rate and altered crop phenology of soybean was observed under elevated CO2 at early stage (V-3/V-4) but showed positive physiologically response at later stage (R3) indicating adoptive mechanism of plants to high CO2. Elevated CO2 decreases number of leaves by 23% and 14% and reduction in leaf area by 11.7% and 9.7% compared to ambient CO2 at 29 and 44 days after planting (DAP), respectively. Adaptive mechanism of plants to high CO2 produced 39% and 83.7% greater leaf number and leaf area, respectively at later stage (R3) of the crop growth (59 DAP). Reduction in specific leaf area (SLA) at 29 DAP (22.2%) but an increase at 44 DAP (1.4%) and 58 DAP (8.5%) under elevated CO2. Dry matter production of plants was increased significantly for elevated CO2. Increase in leaf C (<1%) and reduction in N concentration (6.0-9.5%), increased the C:N ratio of soybean leaves (4.4-12.98%) under elevated CO2. Elevated CO2 with normal soil moisture condition produced maximum number of pods (54.8-122.4%) and increase in dry weight of pods (29.8-56.6%). Plants under elevated CO2 produced significantly greater number of root nodules per plant by 114% compared to plants under ambient CO2 at 44 DAP. These results show a direct and interactive effect of elevated CO2 and soil moisture on plant growth that will affect not only the global food security but also nutritional security.