VARIATION OF LEAF GAS EXCHANGE PARAMETERS WITHIN THE CANOPY OF RUBBER (Hevea brasiliensis)
Asian Journal of Plant and Soil Sciences,
The main objective of this study was to investigate the variation of leaf gas exchange parameters of Rubber (Hevea brasiliensis Muell. Arg.) within the canopy of tapped trees of two Hevea genotypes, I.e. RRIC121 and RRISL 211. The leaf gas exchange parameters, I.e.Stomatal conductance (gs),Intercellular CO2 concentration (Ci), Leaf temperature (Tleaf),Transpiration rate ( E ),Water use efficiency (WUE) and Leaf-air vapour pressure deficit (lvpd) were measured under optimal environmental conditions. Study findings clearly revealed that the intercellular CO2 concentration (Ci) gradually decrease with increasing light intensity in both clones. The same trend was observed in the different canopy layers under both tapping treatments.Clone RRISL 211 showed a higher leaf temperature than RRIC 121 under tapping. The highest leaf-air vapour pressure deficit (lvpd) was shown in the leaves of the upper canopy and lowest in the bottom canopy layer. Furthermore, the water use efficiency (WUE) of clone RRISL 211 was higher than that of clone RRIC 121 under tapping. In the tapped treatment, because of tapping, the photosynthetic rate is stimulated relative to the transpiration rate. The positive latex yield response to WUE and lvpd of top leaves indicates that, in top leaves when lvpd increases transpiration also increases accordingly. Clone RRIC 121 showed a greater contribution from the middle layer to overall canopy photosynthesis while RRISL 211 showed a lower contribution. This could have been due to the more open canopy architecture in clone RRIC 121 or maintenance of a higher A in low light levels.
- leaf gas exchange parameters
- canopy layers
How to Cite
Gomez JB. Physiology of latex (Rubber) production. Malaysia Rubber Research and Development Board, Kuala Lumpur, Malaysia. 1983;71-98.
Nugawela A. Gas exchange characteristics of Hevea genotypes and their use in selection for crop yield. Ph.D. Thesis, University of Essex, England; 1989.
Beadle CL, Long SP, Imbamba SK, Hall DO, Olembo RJ. Photosynthesis in relation to plant production in terrestrial environments. Tycooly International, Oxford; 1985.
Monsi M, Uchijima Z, Oikawa T. Structure of foliage canopies and photosynthesis. Ann. Rev. Ecol. Syst. 1973;4:301-327.
Zelitch I. The close relationship between net photosynthesis and crop yield. Bio Science. 1982;32(10): 796-801.
Korpilathi E. Photosynthetic production of scots pine in the natural environment. Acta Forestalia Fennica. 1988;202:1-71.
Aylett GP. Irradiance interception, leaf conductance and photosynthesis in Jamaican Upper Montane Rain Forest Trees. Photosynthetica. 1985;19 (3):323-337.
Pereira JF, Splittstoesser WE, Ogren WL. Photosynthesis in detached leaves of cassava. Photosynthetica. 1986;20(3):286-292.
Von Caemmerer S, Farquhar GD. Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves. Planta. 1981;153:376-387.
Ludlow MM, Wilson GL. Photosynthesis of tropical pasture crops. Illuminance, CO2 concentration, leaf temperature and leaf-air vapour pressure difference. Australian Journal of Biological Science. 1971;24: 449-470.
Long SP, Incoll LD, Woolhouse HW. C4 photosynthesis in plants from cool temperate regions, with particular reference to Spartina townsendii. Nature. 1975;257:622- 624.
De Costa WAJM. Principles of crop physiology: Towards an understanding of crop yield determination and improvement. University of Peradeniya, Sri Lanka. 2000;189-377.
Chazdon RL, Fetcher N. Photosynthetic light environments in a low land tropical rain forest of Costa Rica. Journal of Applied Ecology. 1984;72:553-564.
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