Root and shoot development in winter crops in soils of different textures and degrees of compaction

ABSTRACT Compaction is one of the main physical factors of the soil to affect plant development. The aim of this study was to evaluate root and shoot development in winter plants grown in soils of different textures under varying degrees of soil compaction (DSC). The experiment was conducted in a greenhouse of the State University of Ponta Grossa, in the south of Brazil. Wheat (Triticum aestivum) and an intercropping system of black oats (Avena strigosa) and forage turnip (Raphanus sativus) were tested in a sandy loam Cambisol and a clayey loam Latosol under a DSC of 85%, 90%, 95% and 100% of the maximum bulk density in a completely randomised design with four replications. Each plot consisted of one PVC column, 0.1 m in diameter and 0.2 m in height, comprising three cylinders placed one on top of the other, with a respective height of 0.08, 0.04 and 0.08 m. The sub-surface layer (0.08-0.12 m) was compacted, and corresponded to the middle cylinder. In t he compacted sub-surface layer, the intercropped black oats and forage turnip presented 28.5% more root dry matter (RDM) than did the wheat. The total RDM decreased by 32% for an increase of 85% to 100% in the DSC, where both the compacted sub-surface layer (0.08-0.12 m) and the layer below that (0.12-0.2 m) were most affected, with a reduction of 45.2% and 53%, respectively. Considering the conditions of this study, which evaluated soils that offer no water or chemical restrictions on the plants, shoot dry matter (SDM) was less affected than the roots, decreasing by 12% for an increase of 85% to 100% in the DSC. There was no difference between the types of soil on crop response due to the variation in the DSC.