MECHANISTIC PROCESS-LEVEL CROP SIMULATION MODELS FOR ASSESSMENT OF AGRICULTURAL SYSTEMS
Location: Crop Systems & Global Change
Title: Response of potato gas exchange and productivity to phosphorus deficiency and CO2 enrichment
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 23, 2011
Publication Date: May 1, 2012
Citation: Fleisher, D.H., Wang, Q., Timlin, D.J., Chun, J.A., Reddy, V. 2012. Response of potato gas exchange and productivity to phosphorus deficiency and CO2 enrichment. Crop Science. 52:1803-1815.
Interpretive Summary: Atmospheric carbon dioxide concentration (CO2) is expected to continue to increase with climate change. The growth of many crops, such as potato, can increase with higher levels of CO2. However, plants also need fertilizer in the soil to grow. If the fertilizer amount in the soil is too small, plant growth can actually decrease, even under higher levels of CO2. Other studies have found that many plants need less nitrogen, a fertilizer component, when grown under higher CO2 levels, but few studies have looked at phosphorus, another important fertilizer component. Understanding how a plant’s needs for phosphorus may be affected by CO2 is important in order to improve natural resource use in farm management. Therefore, experiments were conducted to look at how different components of potato growth respond to phosphorus and CO2. Findings indicate that potato plants respond more strongly to the level of phosphorus content in the soil than they do to the CO2 concentration. The research also shows there is a limit in which increasing soil phosphorus amount will not increase potato growth, no matter what the CO2 level is. This information helps scientists understand how higher CO2 levels and soil nutrition affect potato growth and will be used to develop appropriate strategies and tools for potato crop nutrient management. The results benefit scientists, policy planners, crop consultants, and farmers.
The degree to which crops respond to atmospheric carbon dioxide enrichment (CO2) may be influenced by their nutrition level. While the majority of CO2 and plant nutrition studies focus on nitrogen, phosphorus (P) is also required in relatively high amounts for important crops such as potato. To determine the extent to which potato dry matter production, canopy and leaf photosynthesis and transpiration rates are influenced by these factors, potatoes (Solanum tuberosum L. Kennebec) were grown in outdoor soil-plant-atmosphere-research (SPAR) chambers at two levels of CO2 (400 or 800 parts per million, ppm) and three levels of P fertilization. Total dry matter production declined an average 42 percent between high and low P fertilizer and increased 13 percent in response to elevated CO2 when averaged across the P treatments. This enhancement effect did not vary with level of P treatment. Leaf level photosynthetic rate was reduced 58 percent and stomatal conductance 43 percent between high and low P-treatments. Biochemical model parameters for carboxylation rate, ribulose biphosphate regeneration, and triose phosphate utilization were reduced by P deficiency, but scarcely influenced by growth CO2. After tuber initiation, canopy assimilation rate increased under elevated CO2, particularly at the middle levels of P-fertilization, and diurnal canopy evapotranspiration showed a significant reduction in response to elevated CO2 and declining P-fertilizer. Lack of interactive effects between CO2 and P on most measured responses suggests the effect of CO2 enrichment on potato growth and assimilation is similar at each P-treatment level; however, such effects may also be correlated with plant nitrogen status. These results are particularly useful for development of mathematical predictive tools for climate change adaptation.