CO2 Uptake and Water Use Efficiency in Field Grown Azadirachta siamensis and Pterocarpus macrocarpus in Early and Late Winter
Sureeporn Kerdkankaew*, Jesada Luangjame and Pojanie Khummongkol* Author for corresponding; e-mail address: sureekaew@hotmail.com
Volume: Vol.30 No.2 (AUGUST 2003)
Research Article
DOI:
Received: 7 October 2002, Revised: -, Accepted: 26 May 2003, Published: -
Citation: Kerdkankaew S., Luangjame J. and Khummongkol P., CO2 Uptake and Water Use Efficiency in Field Grown Azadirachta siamensis and Pterocarpus macrocarpus in Early and Late Winter, Chiang Mai Journal of Science, 2003; 30(2): 113-121.
Abstract
This study was performed to examine the CO2 uptake of Azadirachta indica A. Juss. var. stamensis (Valeton), a fast-growing tree species, and Pterocarpus macrocarpus Kurz, a slow-growing tree species, both grown in Kanchanaburi province. Field data were taken using the Li-Cor 6200 portable photosynthetic system in December 1999 and February 2000. The results showed that the CO2 uptake rate of A. siamensis was significantly higher than of P. macrocarpus in early winter (December). The highest CO2 uptake of A. siamensis was 13.86 mgCO2 dm-2.hr-1 at around noon, whereas that of P. macrocarpus was only 8.68 mgCO2 dm-2.hr-1. Nevertheless, no differences in the CO2 uptake were observed at the end of the winter (February) in both tree species. Furthermore, the water use efficiency (CO2 uptake per one unit of transpiration) of A. siamensis was lower than that of P. macrocarpus in both periods. In conclusion, the water use efficiency of P. macrocarpus was higher thant of A. siamensis whereas the CO2 uptake rate of A. siamensis was greater than of P. macroparpus.