Relationships between soil structure, root distribution and water uptake of chickpea (Cicer arietinum L.).: Plant growth and water distribution

Root clustering as a consequence of soil compaction has been hypothesised as a cause of reduction in both water uptake and growth of plants. On the basis of such a hypothesis models of water uptake that take root spatial arrangement into account have been proposed. Data to validate such models are scarce, particularly for leguminosae. This research was conducted on chickpea with the aim of studying the spatial distribution of roots and water in growth media of different degrees of compaction. Chickpea var. Sultano was grown in pots containing silty-clay soil with aggregates of < 0.5 cm in diameter for treatment TF (fine soil), and fine soil + a large clod (representing 30-33% of the total soil dry weight) for treatment TF + Z. Each pot was brought to field capacity and covered with mulch to avoid evaporation losses. Plants were grown on stored water. The treatment with homogeneous soil (TF) showed a higher above-and below-ground growth and water uptake compared with those of TF + Z. A hyperbolic relation was found between root density and soil resistance penetration. Roots were distributed quite homogeneously in the fine soil of both treatments, but they colonised only the outer parts of the clods. At the end of the experiment treatment TF + Z showed unextracted water in the clods. The spatial distribution of roots and the plant ability to take up water were strongly affected by soil structural conditions. (C) 2000 Elsevier Science B.V. All rights reserved.