Effects of aeration and soil compaction on growth of the carrot,Daucus carotaL.

Abstract

SummaryGrowth analysis of carrots grown in water culture has shown that dry matter accumulation and growth in size are severely affected by lack of aeration of the medium, top growth being particularly affected. Exposure of the top few cm of the tap root to the air ameliorates this condition to a limited extent. Although plants grown at all times without aeration appear to adapt to such conditions to some degree, a rapid change to non-aerated conditions has disastrous effects and causes severe leaf senescence. Subsequent formation of lateral roots at the upper end of the tap root may serve to increase O2 uptake by the root system. Transfer from non-aerated to fully aerated conditions provokes a rapid increase of top growth, suggesting the involvement of root-produced cytokinins. Soil compaction also has major effects on root growth and length, very loose or highly compacted conditions being detrimental to overall growth. With high compaction normally cylindrical tap roots become sharply conical.