Effects of Stem Density on Potato at Different CO2 Concentrations.

Potato stem density influences growth, canopy formation, and tuber yield.  However, potato canopy development in response to different planting densities has not been completely characterized.  In addition, many potato studies conducted in controlled environment chambers restrict growth of planted seed tubers to a single mainstem.  The assumption in such studies is that observations of potato growth from a single mainstem will be compatible with field studies where multiple mainstems typically form.  In order to test this assumption and characterize differences in canopy growth and development, two 60 day experiments were conducted in six Daylit growth chambers with potatoes maintained at single, double, or triple mainstems per seedpiece.  Ambient (400 ppm) and elevated (800 ppm) atmospheric carbon dioxide concentrations were maintained in each experiment.  Measurements of whole plant gas exchange, light interception, leaf and branch appearance rates, leaf expansion rates, and dry matter production were used to assess differences between stem densities at the different carbon dioxide concentrations.  The results indicate that growth and development between single and multiple stemmed tubers is simlar at either carbon dioxide concentration level.  The data can also be used to improve carbon allocation modeling in indeterminate plant species.