Growth, nutrient dynamics and efficiency responses to carbon dioxide and phosphorus nutrition in soybean

Authors: SINGH, SHARDENDU - University Of Maryland Eastern Shore (UMES); Reddy, Vangimalla; Fleisher, David; Timlin, Dennis

Submitted to: Journal of Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2014
Publication Date: 10/16/2014
Citation: Singh, S.K., Reddy, V., Fleisher, D.H., Timlin, D.J. 2014. Growth, nutrient dynamics and efficiency responses to carbon dioxide and phosphorus nutrition in soybean. Journal of Plant Interactions. 9:838-849.

Interpretive Summary: Plant mineral nutrients such as phosphorus may exert major control on the plant response to the rising atmospheric carbon dioxide (CO2) concentration. The atmospheric CO2 concentration is projected to be doubled by the end of the 21st century. In general, plant growth and productivity increases under high CO2 environment but decreases under phosphorus deficiency. Therefore, it is important to study the combined effect of phosphorus deficiency under current and projected (doubled of the current CO2 of 400 µmol) CO2 concentrations on soybean growth. Results showed that the degree of beneficial effects of high CO2 on soybean growth was reduced as phosphorus deficiency increased. The observed soybean growth stimulation by high CO2 was associated with the increased phosphorus utilization efficiency for biomass production. Phosphorus deficiency led up to 42 percent reduction in seed weight across CO2 concentrations. The required leaf tissue phosphorus concentration for maximum productivity appeared to be higher at high CO2 versus ambient CO2. This work illustrated that the increased CO2 may not benefit soybean growth under severe phosphorus deficient soils. The results will benefit agronomy researchers and soybean growers by highlighting the importance of better soil phosphorus management to maximize soybean yield under the current and projected CO2 enriched atmosphere.

Technical Abstract: Plant mineral nutrients such as phosphorus may exert major control on the plant response to the rising atmospheric carbon dioxide (CO2) concentrations. To evaluate the interactive effects of these two factors on soybean (Glycine Max (L.) Merr.) growth and yield, photosynthesis, biomass partitioning, and allocation of nutrients in the plant organs, plants were grown in a controlled environment growth chambers. There was sufficient (0.50 mM) and deficient (0.10 and 0.01 mM) phosphate (Pi) supply under ambient and elevated CO2 (aCO2, 400 and eCO2, 800 µmol mol-1, respectively). The CO2 ' Pi interactions were observed for leaf area, leaf and stem dry weight and total biomass. The severe decrease in plant biomass in Pi-deficient plants was associated with reduced leaf area and photosynthesis (Pnet). The degree of growth stimulation (0 – 55% final plant biomass) by eCO2 was dependent upon the severity of Pi deficiency and was closely associated with the increased phosphorus utilization efficiency for biomass production. With the exception of leaf and root biomass, Pi deficiency decreased the biomass partitioning to other plant organs with the maximum decrease observed in seed weight (8 – 42%) across CO2 levels. The increased tissue nitrogen (N) conc. in Pi-deficient plants might be attributed to the lower biomass and increased nutrient uptake due to large fraction of root mass to the total biomass. The tissue P and N conc. tended to be lower under elevated CO2; however, it did not appear to be cause of the lack of response of growth and Pnet under Pi deficiency. Although P and N remobilization from leaves to seeds were apparent, the increase conc. of these elements in the abscised leaves was also observed. The tissue P conc. needed to attain the maximum productivity for photosynthesis, biomass and seed yield tended to be higher at eCO2 versus aCO2. Therefore, the eCO2 is likely to alter the leaf critical conc. for biomass productivity and yield in soybean.