Productivity of leaves of a tropical tree, Theobroma cacao, grown under shading, in relation to leaf age and light conditions within the canopy
Article first published online: 28 JUN 2008
Volume 137, Issue 3, pages 463–472, November 1997
How to Cite
MIYAJI, K.-I., DA SILVA, W. S. and ALVIM, P. d. T. (1997), Productivity of leaves of a tropical tree, Theobroma cacao, grown under shading, in relation to leaf age and light conditions within the canopy. New Phytologist, 137: 463–472. doi: 10.1046/j.1469-8137.1997.00841.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- (Received 22 January 1997; accepted 25 June 1997)
- Canopy irradiance;
- leaf photosynthesis and respiration;
- Theobroma cacao (cacao)
The photosynthetic and respiratory activities of the leaves of a tropical tree, cacao, Theobroma cacao L., grown under shading, were determined in relation to leaf age and light conditions within the canopy, in order to gain a deeper insight into characteristics of the leaf population composing a canopy.
The specific leaf weight and leaf water content varied with the height of leaves from the ground and/or the irradiance. The net photosynthetic rate also varied markedly depending on leaf age and irradiance. The leaves in full or nearly full irradiance (< 70% full daylight) attained the maximum rater. 60 d after the leaves emerged, and the rate decreased to nearly zero at a leaf age of c. 270 d.
The nocturnal leaf respiratory activity was proportional to the photosynthetic activity during the day, but the proportional ratio was not constant throughout the survival period of leaves. Within the closed canopy, the upper leaves, which much higher ratios of respiratory to photosynthetic activity, under full or nearly full irradiance, tended to have much shorter mean longevities (c. 160 d) than the lower leaves under a lower irradiance (c. 310 d).