ACID-RAIN - ACIDIC MIST-INDUCED RESPONSE IN GROWTH AND PHOTOSYNTHETICACTIVITIES ON CROP PLANTS

Experiments were conducted in the field to investigate the influence o f acidic mists treatment on height, biomass, leaf chlorophyll, net pho tosynthesis, and photosystem activities in Vigna sinensis L. and Phase olus mungo L. Plants exposed to different acidic mists (pH 5, 4, 2) fo r 5 days showed significant reduction in height and biomass accumulati on. The level of chlorophyll on a unit fresh weight basis showed progr essive reduction upon increasing acidity of mists treatment; the reduc tion was due to the loss of Chi a and Chl b. Leaf-soluble protein was not significantly reduced. The increased stomatal diffusive resistance and reduced photosynthetic pigments lowered the net photosynthetic ra te. However, when various photosynthetic activities were followed in i solated chloroplast, a decrease in the rates was obtained in the seedl ings exposed to pH 4 and 2. No significant change in photosystem I act ivity was observed at various acidic mists treatments. Analysis of chl oroplast polypeptides indicates specific loss of 33, 23, and 17 kDa ex trinsic polypeptides.