Root elongation of seedling peas through layered soil of different penetration resistances |
| |
Authors: | A G Bengough I M Young |
| |
Institution: | (1) Soil-Plant Dynamics Group, Department of Cellular and Environmental Physiology, Scottish Crop Research Institute, DD2 5DA Dundee, UK |
| |
Abstract: | Field soils contain localized zones of larger penetration resistance within peds and compacted layers, while cracks and biopores
offer low resistance pathways to roots. Root responses to such localized conditions have not been investigated in detail.
This study examined what happens to the root elongation rate when roots grew through a layer of hard soil into a layer of
looser soil for a 4 day period.
The experiment was performed twice; firstly with the shoot in continuous darkness, and secondly with it exposed to a day-night
cycle to prevent etiolation of the shoot. Pea seedlings were grown in columns of a sandy loam soil which was packed to bulk
densities of 0.85, 1.1, 1.3 or 1.4 Mg/m3 in the top layer and 0.85 Mg/m3 in the bottom layer.
The root elongation rate in the top layer of 1.4 Mg/m3 soil (penetrometer resistance=1.8 MPa) was only 55% of the elongation rate in the top layer of 0.85 Mg/m3 soil (penetrometer resistance=0.06 MPa). The elongation rate of roots that had grown through the top layer of 1.4 Mg/m3 soil into the bottom layer of loose soil was reduced by some residual effect of the mechanical impedance. The root elongation
rate in the bottom layer of loose soil decreased as the penetrometer resistance of the top layer of soil increased. The daily
elongation rate of the roots in the bottom layer that had grown through the 1.4 Mg/m3 soil averaged only about 65% of the elongation rate of the roots that had grown through the 0.85 Mg/m3 soil.
This residual effect of mechanical impedance on root elongation persisted for at least 2 days and was more severe in the day-night
cycle experiment than in the dark experiment. These results have important implications for modelling root elongation in any
soil in which the soil strength changes with distance or with time. |
| |
Keywords: | compaction mechanical impedance penetrometer Pisum sativum root diameter sandy loam shoot elongation soil strength |
本文献已被 SpringerLink 等数据库收录! |
|