Root Distribution of Peach Rootstocks Affected by Soil Compaction and Acidity

Abstract

Root growth can be limited by physical and chemical conditions of the soil. Compacted and acidic soils, where there is an occurrence of exchangeable Al, constitute barriers to use of the soil by plant roots. The hypothesis of this study was that physical and chemical properties of the inter-row soil of a peach orchard influence the root distribution of different rootstocks. The aim of this study was to describe and register the soil physical and chemical properties and root distribution in the soil profile of the inter-row of seven years old mature peach (Prunus persica) orchard. Samples of soil (classified as an Argissolo Vermelho Distrofico tipico [Rhodic Paleudult] with 180 g kg-1 clay, 120 g kg-1 silt, and 700 g kg-1 sand) and roots were collected from orchard inter-rows of ‘Maciel’ peach, grafted onto ‘Okinawa’ and ‘Nemaguard’ rootstock, at 1.5, 2.0, and 2.5 m from the trunk, and at every 0.10 m, up to a depth of 0.50 m. The soil samples were sieved and the roots washed. A subsample was removed from each sample for chemical analysis. Resistance to penetration (RP) was used as an indicator of soil compaction. A close relationship was found among chemical properties, RP, and root distribution. Root density was affected by the presence of compacted regions (RP >2,000 kPa) and by high Al saturation in the exchange complex in the soil profile. There was a reduction in the frequency of thick roots (O >2 mm) in the samples collected in portions of compacted soil and at increasing soil depth. The compacted portion of the inter-row limits lateral distribution of the peach tree root system, while aluminum limits its depth.