Heterogeneous Salt Concentrations in Soil Affects Pyrus calleryana Decne. Growth

The uneven salt distribution in soil plays an important role in regulating plant growth. To explore the effect of heterogeneous soil salt stress on the growth of Pyrus calleryana Decne., container seedlings were placed in a split-root container for salt stress treatment. Five salt stress root treatments were performed, including a control non-salt stress treatment, two localized salt stress treatments, and two whole-root uniform salt-stress treatments. Our results indicate that salt stress was directly related to the reduced growth and photosynthesis. Seedlings under localized salt stress treatments (0/100 and 0/200) showed significantly larger increases in biomass than those under uniform salt stress treatments (100/100 and 200/200).Under localized salt stress treatment (0/100), the compensatory growth of fine roots (d < 2 mm) occurred in the salt-free side of the plant container, and the fine root biomass, root length, surface area, root volume, root tip number, branch number, and crossing number on the non-salt-stressed side were significantly higher compared to those on the salt-stressed side. Under the localized salt-stress treatment of 0/200, the salt concentration exceeded the lethal concentration for roots, which led to the growth of fine roots on the salt-free side. Our results indicate that the compensatory growth of L-side fine roots increased the photosynthetic rate and dry matter accumulation, and reduced the inhibition on the growth of Pyrus calleryana under local salt stress compared with uniform salt stress.