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.
Micro-suction cups were installed in split-root 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 (Fe3+/Mn2+, Na+) and anions (Cl-, SO4 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.
Zhang, J.; George, E. 2009. 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. Plant and Soil 322, 209-218.