CARBOHYDRATE RESERVES ON TAPPING SYSTEMS AND PRODUCTION
OF Hevea brasiliensis
Chantuma P1., Lacointe A2., Kasempsap P3., Thanysawanyangkura S4., Gohet E5.,
Clément A6., Guilliot A7., Améglio T2., Thaler P8. and Chantuma A1.
1 Agriculture Scientist Senior, Chachoengsao Rubber Research Center, RRIT-DOA, Ministry of Agriculture and Cooperative, Sanam Chai Ket, Thailand.
2 INRA, UMR 547 PIAF, F-60100 Clermont-Ferrand, France.
3 Department of Horticulture, Faculty of Agriculture, Kasetsart University, 10900 Bangkok Thailand.
4 DORAS Center, Kasetsart University, 10900 Bangkok Thailand.
5 Cirad, UPR Systèmes de pérennes, DORAS Center, Kasetsart University, 10900 Bangkok, Thailand ; Cirad, UPR Systèmes de pérennes, Montpellier, F-34000, France.
6 Cirad, UPR Adaptation Agroécologique et Innovation Variétale, Montpellier, F-34000, France.
7 Université Blaise Pascal, UMR 547 PIAF, F-63177 Aubiere, France
8Cirad, UPR Ecosystèmes de plantation, DORAS Center, Kasetsart University, 10900 Bangkok, Thailand ; Cirad, UPR Ecosystèmes de plantation, Montpellier, F-34000, France.
Corresponding author : pisamaichantuma@hotmail.com
ABSTRACT
Trees rely on carbohydrate reserves stored in parenchyma when the current level of carbohydrates produced by photosynthesis is not enough to meet the demand for maintenance, growth or metabolism. However, an increased C demand does not necessarily result in a depletion of carbohydrate concentration in wood, additional sink created by tapping or harvesting resulted not in a decrease, but an increase in total carbohydrate reserves. In the present study, the dynamic response of C reserves to tapping was further investigated regarding compartmentalization and chemical fractions. Three tapping systems were compared to the untapped control for 2 years. Soluble sugars and starch were analyzed in bark and wood on both sides of the trunk, from 50 cm to 200 cm from ground. We confirmed that variations in TNC relied mainly on starch and that tapped trees had higher starch and TNC than controls. Moreover, a double cut alternative system (DCA), which produced a higher yield than conventional systems tapped on one side only, lead to even higher carbohydrate concentrations. Whereas the tapped side had lower starch concentration than the untapped in conventional systems, DCA-treated trees exhibited high starch concentration in both sides. SS was higher in bark, where latex regeneration occurs, than in wood, whereas it was the contrary for starch and TNC.
From seasonal dynamics and differences between the 2 sides of the trunk in response to tapping, we concluded that starch in wood behaved as the long-term reserve compartment acting at the whole plant level, whereas starch in bark and SS behaved more like intermediate, ready-to-use compartments. Finally, the dynamics of carbohydrate reserves appears to be a relevant parameter to assess long term performance of tapping systems.
