Fate of carbon in upland grassland subjected to liming using in situ 13CO2 pulse-labelling

Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help understand how rubber trees face this additional C demand. Whole crown 13CO2 pulse labelling was performed on 4-year-old rubber trees in June when latex production was low and in October, when it was high. 13C contents were quantified in the foliage, phloem sap, wood and latex. In both labelling periods, 13C was recovered in latex just after labelling, indicating that part of the carbohydrates was directly allocated to latex. However, significant 13C amounts were still recovered in latex after 100 days and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October than in June. An improved understanding of C dynamics and source-sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production.

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Fast assimilate turnover revealed by in situ 13CO2 pulse-labelling in Subarctic tundra

Polar Biology ◽

10.1007/s00300-012-1167-6 ◽

2012 ◽

Vol 35 (8) ◽

pp. 1209-1219 ◽

Cited By ~ 9

Author(s):

Jens-Arne Subke ◽

Andreas Heinemeyer ◽

Harry W. Vallack ◽

Vincenzo Leronni ◽

Robert Baxter ◽

...

Keyword(s):

Pulse Labelling

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In situ dynamics of recently allocated 14C in pasture soil and soil solution collected with Rhizon Soil Moisture Samplers

Soil Research ◽

10.1071/sr04107 ◽

2005 ◽

Vol 43 (5) ◽

pp. 659 ◽

Cited By ~ 6

Author(s):

Bhupinderpal-Singh ◽

M. J. Hedley ◽

S. Saggar

Keyword(s):

Soil Moisture ◽

Soil Solution ◽

Soil Surface ◽

Pulse Labelling ◽

Short Term ◽

Microbial Decomposition ◽

Different Depths ◽

Non Destructive ◽

Soil Interface

Information on the dynamics of recently photo-assimilated carbon (C) allocated to roots and root-derived exudates in soils is scarce and experimentally difficult to obtain. We used Rhizon Soil Moisture SamplersTM (RSMS) placed at different depths in soil (20, 40, 80, 120 mm) to monitor short-term dynamics of root and root-derived C at the root–soil interface after 14CO2 pulse-labelling of pasture cores. At the 20 mm depth, 14C activity in soil solution peaked within 2 h of 14CO2 application. The peak of 14C activity took longer to appear and slower to disappear with increased depth. Negligible amounts of 14C as soluble exudates were found in the soil solution. The pattern of initial 14C activity in soil solution, allocation of recently assimilated 14C in roots, and root mass distribution with depth were closely related to each other. This suggested that the rapid appearance of 14CO2 in soil solution is more closely linked to root respiration of recent 14C-assimilates (transferred via shoots to roots) and/or to microbial decomposition of root-released 14C-assimilates than to transfer by diffusion of atmospheric 14CO2 through open soil surface to different depths in soil. The use of RSMS was an effective, simple, and non-destructive method to monitor the dynamics of root-derived 14C by in situ sampling of soil solution.

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In situ 13CO2 labelling of rubber trees reveals a seasonal shift in the contribution of the carbon sources involved in latex regeneration

Journal of Experimental Botany ◽

10.1093/jxb/erz551 ◽

2020 ◽

Vol 71 (6) ◽

pp. 2028-2039

Author(s):

Ornuma Duangngam ◽

Dorine Desalme ◽

Philippe Thaler ◽

Poonpipope Kasemsap ◽

Jate Sathornkich ◽

...

Keyword(s):

Rubber Tree ◽

Carbon Sources ◽

Pulse Labelling ◽

Phloem Sap ◽

Latex Regeneration ◽

Source Sink ◽

13Co2 Labelling ◽

Latex Biosynthesis ◽

Latex Production

Abstract Rubber trees (Hevea brasiliensis) are the main source of natural rubber, extracted from latex, which exudes from the trunk after tapping. Tapped trees require large amounts of carbon (C) to regenerate the latex after its collection. Knowing the contribution of C sources involved in latex biosynthesis will help in understanding how rubber trees face this additional C demand. Whole crown 13CO2 pulse labelling was performed on 4-year-old rubber trees in June, when latex production was low, and in October, when it was high. 13C content was quantified in the foliage, phloem sap, wood, and latex. In both labelling periods, 13C was recovered in latex just after labelling, indicating that part of the carbohydrate was directly allocated to latex. However, significant amounts of 13C were still recovered in latex after 100 d and the peak was reached significantly later than in phloem sap, demonstrating the contribution of a reserve pool as a source of latex C. The contribution of new photosynthates to latex regeneration was faster and higher when latex metabolism was well established, in October, than in June. An improved understanding of C dynamics and the source–sink relationship in rubber tree is crucial to adapt tapping system practices and ensure sustainable latex production.

Download Full-text