'Penerbit Universiti Kebangsaan Malaysia (UKM Press)'
Abstract
Elevated atmospheric carbon dioxide causes changes in most plant species in terms of physiological and morphological
properties. In this study, we elucidate the effects of elevated CO2 and water regimes on two species of shrubs which were
Melastoma malabathricum and Clidemia hirta. The factor of water stress was also included whereby for each CO2 treatment,
the amount of water was given once or twice daily. The treatment of elevated CO2 was at 800 ppm, where the plants were
exposed for two hours daily and ambient CO2 at 400 ppm as the control. The growth of plants was monitored through their
height, leaf area and biomass that were recorded fortnightly for six months. The physiological changes were determined via
stomatal conductance, photosynthetic rate and transpiration rate. The results revealed that each species responded differently
to the CO2 treatments. The growth parameters of height and leaf area index showed positive responses on elevated CO2 and
twice watering for both species. As for biomass, M. malabathricum exhibited higher below ground biomass compared to
above ground biomass in the elevated CO2. In contrast, C. hirta showed the opposite trend. The results of the three physiological
parameters demonstrated a bell shape trend for both treatments with the highest rate at the fifth month