Abstract
The release of rhizodeposits differs depending on the root position and is closely related to the assimilated carbon (C) supply. Therefore, quantifying the C partitioning over a short period may provide crucial information for clarifying root–soil carbon metabolism. A non-invasive method for visualising the translocation of recently assimilated C into the root system inside the rhizobox was established using 11CO2 labelling and the positron-emitting tracer imaging system. The spatial distribution of recent 11C-photoassimilates translocated and released in the root system and soil were visualised for white lupin (Lupinus albus) and soybean (Glycine max). The inputs of the recently assimilated C in the entire root that were released into the soil were approximately 0.3%–2.9% for white lupin within 90 min and 0.9%–2.3% for soybean within 65 min, with no significant differences between the two plant species; however, the recently assimilated C of lupin was released at high concentrations in specific areas (hotspots), whereas that of soybean was released uniformly in the soil. Our method enabled the quantification of the spatial C allocations in roots and soil, which may help to elucidate the relationship between C metabolism and nutrient cycling at specific locations of the root–soil system in response to environmental conditions over relatively short periods.
Highlights
The release of rhizodeposits differs depending on the root position and is closely related to the assimilated carbon (C) supply
The inputs of the recently assimilated C in the entire root that were released into the soil were approximately 0.3%–2.9% for white lupin within 90 min and 0.9%–2.3% for soybean within 65 min, with no significant differences between the two plant species; the recently assimilated C of lupin was released at high concentrations in specific areas, whereas that of soybean was released uniformly in the soil
Our method enabled the quantification of the spatial C allocations in roots and soil, which may help to elucidate the relationship between C metabolism and nutrient cycling at specific locations of the root–soil system in response to environmental conditions over relatively short periods
Summary
The release of rhizodeposits differs depending on the root position and is closely related to the assimilated carbon (C) supply. Non-invasive approaches have been developed to sample the soil solution near the roots[5,9] These methods are useful for sampling the integrated amounts of released rhizodeposition sets at daily or weekly intervals during the plant growth period. A method that enables the quantitative analysis of short-term photoassimilate transport into the root and the surrounding soil with positional information is desirable for clarifying the C release capabilities at specific root positions. Imaging methods based on pulse-labelling of 14C have been applied to visualise the allocation of photoassimilates in the roots and surrounding area as rhizodeposits. The PETIS allows the visualisation of C translocation into the soil-grown root system because of the high energy of the gamma-rays (511 keV) from 11C that can permeate the soil[13,28] This may have been because of technical difficulties in distinguishing a small amount of 11C-photoassimilates in the surrounding soil from the much larger amounts of 11C-photoassimilates in the adjacent roots
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call