Novel Topological-Architectural Parameters of Root Growth in Soybean (Glycine max (L.) Merrill) to Determine the Presence of Soil Mechanical Impedance

Objectives: Mechanical impedance causes structural changes in ischolar_mains. Nevertheless, little is known about the changes in soybean ischolar_main systems grown under compacted soils (mechanical impedance). The aim of this work was to understand the morphological and topological-architectural changes occurred in plants ischolar_main system of soybean grown under soil compaction. Methods/Analysis: Three experiments were carried out and three mechanical impedance levels were tested. Silt loam soil passed through a 2-mm-mesh sieve (Typic Argiudol Esperanza series) was used. Three soil compaction levels were determined: 1.1 g.cm^-3, null mechanical resistance (NR); 1.3 g.cm^-3, low mechanical resistance (LR); and 1.5 g.cm^-3, corresponding to high mechanical resistance (HR). Three soil resistances were consequent determine: < 0.1 MPA, 0.5 MPa and 3.5 MPa, respectively. Morphological, geometrical and topological-architectural ischolar_mains parameters were measured. Findings: Plants grown in HR conditions had a ischolar_main system confined to the first centimeters of the ground and showed shorter total ischolar_main length, less number of lateral ischolar_mains, higher diameter and low specific length. Growth form of ischolar_main systems was sensitive to soil mechanical impedance even at resistance levels lower than 1 MPa. As soil impedance increases, lateral ischolar_main growth occurs via the principal ischolar_main rather than via the secondary ischolar_mains and there were higher numbers of lateral ischolar_mains on the principal ischolar_main in the area from the proximal zone to the stem base. Novelty/Improvement: The main differences among NR, LR and HR plants were due to changes in the characteristics of the ischolar_main system rather than in the shoot system, particularly in the ischolar_main growth zone. As a conclusion, the present research demonstrates that there are morphological parameters that can be used to determine if crops have been exposed to soil computation.