Journal of Oil Palm Research Vol. 3 No. 2 1991 Dec, p. 336-348 HENSON, I E*
Leaves from palms of different ages were examined for stomatal distribution, stomatal density, conductance to water vapour, and photosynthetic properties. Leaflets of mature (c. 12-year old) palms had stomata predominantly on the lower (abaxial) surface with few, if any, on the upper (adaxial) surface. Adaxial stomata were more evident in young palms (up to the first year after field planting).
Stomatal density (defined as total number of stomata per unit leaf area) increased progressively with age up to the second year in the field. Leaf conductance and photosynthesis rates, although very dependent on environmental factors, also increased with age, most markedly during the time of first fruit maturation. Photochemical efficiency increased with age of palm in parallel with increases in maximum rate of photosynthesis, while other photosynthetic characteristics either changed little (viz. carboxylation efficiency, photorespiration) or varied more with long term light environment (light compensation point, dark respiration rate) than with palm age.
The involvement of various factors in the increased photosynthetic capacity, and its significance for palm productivity and progeny selection, are discussed.
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* Palm Oil Research Institute of Malaysia,
P O Box 10620,
50720 Kuala Lumpur