Photosynthetic, metabolic and growth responses of Triumfetta rhomboidea to coal-smoke pollution at different stages of plant ontogeny

Abstract

Coal-smoke emissions affected photosynthesis, N-metabolism and growth characteristics of Triumpfetta rhomboidea, as observed at pre-flowering, flowering and post-flowering stages of plant growth. The net photosynthetic rate and stomatal conductance decreased, whereas intercellular CO2 concentration increased under pollution stress. The amounts of photosynthetic pigments in leaves were consistently less, up to 35% for chlorophylls and 84% for carotenoids. Nitrate level was raised while NR activity and protein contents in leaves declined at the polluted site at each growth stage. Sugar content was always lower at the polluted site in roots and stem but sizably higher in leaves, thus showing a failure of the process of photosynthate translocation. The sulphur level in roots, stem and leaves increased consistently. The leaf area was conspicuously reduced, leading to a significant loss in the total photosynthetic surface, despite an increase in the stem length and the number of leaves in the stressed population.