Rhizosphere effects on ion concentrations near different root zones of Norway spruce (Picea abies (L.) Karst.) and root types of Douglas-fir (Pseudotsuga menziesii L.) seedlings

Abstract

Micro-suction cups were installed in splitroot rhizotrons to investigate changes of ion concentrations pertaining to different root zones (Norway spruce) or various root types (Douglas-fir). Plant seedlings were grown in mineral soils fertilised with a mix of KMgCa or unfertilised. In Norway spruce, ions accumulated mostly in the rhizosphere near root tips in fertilised soil. Cations (Fe 3+ /Mn 2+ , Na + ) and anions (Cl -, SO 4 2-) were depleted in basal root areas in unfertilised soil. In Douglas-fir, ion accumulations (except K in unfertilised soil) occurred in rhizosphere of current-year suberized roots in both fertilised and unfertilised soils. Ion concentrations in rhizosphere of one-year-old suberized roots were highest compared to those of newly-grown or current-year roots in fertilised soil. These data demonstrate that soil solution chemistry clearly differs in rhizosphere of different segments of single roots and various root types. Ion accumulation in rhizosphere may be due to high mass flow transport of ions to root surfaces, and the accumulation of ions in rhizosphere was more distinct for root tips.

Nitrogen transformations in the rhizosphere of different tree types in a seasonally flooded soil

“…Though there is limited quantitative information on root exudates of mature trees under natural conditions due to technical difficulties, experiments on tree seedlings revealed that tree species differ greatly in the amount and type of root exudates (Grayston et al 1996, Zhang andGeorge 2009). Different magnitude of rhizosphere effects on MBC, MBN and microbial biomass C:N ratio in the present study also suggests that the amount and quality of root exudates differed among tree species.…”

Seasonal Evolution of the Rhizosphere Effect on Major and Trace Elements in Soil Solutions of Norway Spruce (<i>Picea abies Karst</i>) and Beech (<i>Fagus sylvatica</i>) in an Acidic Forest Soil

“…These latter suggest that the formation of mica-like minerals in the rhizosphere in spring results from the presence in the rhizosphere solution of large amounts of K possessing a strong affinity for the high charge expandable phyllosilicate like vermiculite, which become fixed in the interlayer space [24] [44]. In addition, the accumulation of nutrients in the rhizosphere solution has already been observed in other forest sites under Douglas-fir [24] [45] and Norway spruce [20]. However, a depletion of cations (such as K, Mg and Ca) in the rhizosphere solutions was also observed during tree growth [21] [22] [46].…”

Split-root system as a useful tool to study woody plant biology

“…The use of the SRS of spruce (Picea abies; Pinaceae) and Douglas fir (Pseudotsuga menziesii; Pinaceae) in rhizotrons with a transparent front plate where microsuction cups were installed in the rhizosphere of the root made it possible to assess ion concentrations in individual root zones (Zhang and George 2009). The soil solution chemistry differs in the rhizosphere of various root types and different segments of single roots, and the high water consumption of the above-ground part causes the roots to take up more water than nutrients, leading to the accumulation of nutrients in the rhizosphere.…”