Response of Potato Gas Exchange and Productivity to Phosphorus Deficiency and Carbon Dioxide Enrichment
2012
Fleisher, David H. | Wang, Qinguo | Timlin, Dennis J. | Chun, Jong-Ahn | Reddy, V. R.
The degree to which crops respond to atmospheric CO₂ enrichment may be influenced by nutrition. To determine the extent to which dry matter production, canopy and leaf photosynthesis, and transpiration are influenced by P and CO₂, potatoes (Solanum tuberosum L. cultivar Kennebec) were grown in outdoor soil–plant–atmosphere research (SPAR) chambers at two levels of CO₂ (400 or 800 μmol mol⁻¹) and three levels of P fertilization. Total dry matter declined an average 42% between high and low P fertilizer and increased 13% 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% and stomatal conductance 43% between high and low P treatments. Biochemical model parameters for carboxylation rate, ribulose bisphosphate regeneration, and triose phosphate use 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 N status.
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