Root uptake of N-containing and N-free low molecular weight organic substances by maize: A C/N tracer study |
| |
Authors: | Christian Biernath Holger Fischer Yakov Kuzyakov |
| |
Institution: | aInstitute for Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Str., Ökologiegeb 2, BA 227, 70593 Stuttgart, Germany;bInstitute of Soil Science and Land Evaluation, University of Hohenheim, Emil-Wolff-Str. 27, 70593 Stuttgart, Germany;cDepartment of Agroecosystem Research, University of Bayreuth, 95440 Bayreuth, Germany |
| |
Abstract: | Most studies showing potential organic nitrogen uptake were conducted with amino acids. They conclude that, in some ecosystems, amino acids significantly contribute to the N demand of plants and that roots have special transporters to re-uptake amino acids released into the rhizosphere. However, the relevance of the uptake of organic N compounds can only be evaluated by comparing the uptake of N-containing and N-free organic substances. We compared the uptake of alanine, glucose and acetate labelled with 14C by maize. Additionally, the N uptake was estimated by 15N labelled alanine and KNO3. We found a similar uptake of 14C from alanine, glucose and acetate, amounting for the whole plant less than 1% of 14C input. These results show that maize did not prefer N-containing to N-free organic substances. The uptake of 15N by maize exceeded that of 14C (10- to 50-fold), irrespective of the 15N source. However, plant uptake of nitrate (23.6–35.2% of 15N input) always exceeded the uptake of N from alanine (9.6–28.8%). The uptake of organically bound N by maize growing in soil occurred mainly by transpiration flow – as dissolved organics. The contribution of specific amino acid transporters was minor. |
| |
Keywords: | Re-sorption Maize Uptake Low molecular weight organic substances Alanine Glucose Acetate Nitrate 14C 15N |
本文献已被 ScienceDirect 等数据库收录! |
|