Atmospheric CO₂ Enrichment of Potato in the Subarctic: Root Distribution and Soil Biology

抄録

The effect of increasing atmospheric CO₂ concentration on fine root distribution of potatoes and associated soil biology activity under subarctic conditions has not been studied. Potatoes (Solanum tuberosum L.) were grown in open top field chambers at three CO₂ concentrations [ambient (A) ; A+175μmol mol^-1 CO₂ (A+175) ; A+350 μmol mol^-1 CO₂ (A+350) ] and in ambient CO₂ plots with no chambers (ANC) on a Tanana silt loam (non-acid loamy, mixed Pergelic Cryaquept) at Fairbanks, AK in 1994. Soil cores to a depth of 60 cm were taken at 0, 19, and 38 cm perpendicular to row center; root variables were ascertained at four 15 cm depth increments. Soil cores to a depth of 15 cm were also collected to assess soil biology (dehydrogenase activity, nematodes, and soil microarthropods) . Elevated CO₂ did not enhance root densities (i.e., both length and mass) at any depth or row position; there was no significant CO₂×depth, CO₂×position, or CO₂×depth×position interactions for measured root variables. Significant depth×position interactions were noted. In general, a higher proportion of the potato root system grew closer to the row center (root length and mass bases) most notably at the uppermost soil depths. Elevated CO₂ had no impact on the soil biology parameters evaluated in this study. Our field results suggest that increased atmospheric CO₂ concentration did not alter belowground responses in potato under subarctic conditions of Alaska.