Clonal differences in photosynthesis in Hevea brasiliensis Mull. Arg.

Citation
Kn. Nataraja et J. Jacob, Clonal differences in photosynthesis in Hevea brasiliensis Mull. Arg., PHOTOSYNTHE, 36(1-2), 1999, pp. 89-98
Citations number
30
Categorie Soggetti
Plant Sciences
Journal title
PHOTOSYNTHETICA
ISSN journal
03003604 → ACNP
Volume
36
Issue
1-2
Year of publication
1999
Pages
89 - 98
Database
ISI
SICI code
0300-3604(1999)36:1-2<89:CDIPIH>2.0.ZU;2-0
Abstract
The objective of the present investigation was to examine the extent of var iations in single leaf net photosynthetic rate (P-N) and its relative depen dence on stomatal conductance (g(s)) and the mesophyll capacity to fix carb on in 12 clones of the natural rubber plant. There were significant variati ons in P-N measured at low and saturating photon flux density (PFD); the ex tent of variation was larger at low than at saturating PFD. The compensatio n irradiance (CI) and apparent quantum yield of CO2 assimilation (phi(c)) c alculated from the P-N/PFD response curves showed significant variations am ong the clones. P-N at low irradiance was positively correlated with phi(c) . Thus a clone with large P-N at low irradiance, high phi(c), and low CI ma y tolerate shade better and thus produce a high tree stand per hectare. A s trong positive correlation existed between P-N saturated with radiant energ y (P-sat) and carboxylation efficiency (CE) estimated from the response cur ves of PN on intercellular CO2 concentration (C-i), but g(s) showed a poor correlation with P-max. High CO2 compensation concentration (Gamma) led to low CE in Hevea clones. A clone with large P-sat, high CE, low g(s), and lo w Gamma is the one in which photosynthesis is more dependent on the mesophy ll factors than stomata. Such a clone may produce relatively high biomass a nd maintain high water use efficiency.