The present study is an attempt to assess the growth and biochemical responses of Pongamia pinnata grownunder elevated levels of CO2 supply. Saplings (18 months) maintained in the nursery were brought toexperimentation in two growth chambers having controlled supply of air and air- CO2 mixture, for a periodof 15 days. The control and treated chambers were retained at an average CO2 concentration of 505.28±17.39 ppm and 1053.85± 24.99 ppm respectively. Day and night fluxes of CO2 within the chambers wereanalysed daily, along with a periodic assessment of the growth and biochemical responses associated withthe plants. A standardization study, excluding plants, was also attempted to assess the resultantflux ofCO2 associated with the growth chambers. The day flux of CO2 in the control and treatedchambers wasdifferent from that of the night flux in both experimentation and standardization studies. Higher CO2assimilation by the plants in the CO2 enriched system during the day time has also resulted in increasedplant height, stem thickness, leaf area and also in the assimilation of carbohydrates, sodium and potassium.Increased Carotenoids and phenol are implications of the stress to which the plants are subjected to underelevated levels of CO2 supply. The present study confirms that, despite certain signs of stress, Pongamiapinnata can be an ideal candidate for carbon offset planting.

Leaching potential of pesticides, apart from climatological factors, depends on soil physical properties, soil-pesticide interaction and chemical nature of the molecule. Recent investigations have revealed the presence of various organophosphate pesticides in various agroecosystems. The present study investigated the soil transport mechanism of commonly used organophosphate pesticides in acidic sandy clay loam soils of Kerala State, India. Packed soil column experiment was undertaken under laboratory condition for 30 days. Unsaturated flow was carried out using distilled water/0.01 M CaCl solution after applying chlorpyriphos and quinalphos at the rate of 0.04% a.i.ha and 0.025% a.i.ha, respectively. The study revealed the retention of residues of chlorpyriphos and quinalphos in the top 5-cm layer. Irrespective of the applied concentration of chlorpyriphos and quinalphos, the relative concentration of the pesticides in soil was similar. About 56% of the applied chemicals were dissipated in 30 days of unsaturated flow. A new dissipation compound iron, tricarbonyl [N-(phenyl-2-pyridinylmethyene) benzenamine-N, N'], was detected in GCMS analysis of soil extract from distilled water percolated soil. The dissipation of chlorpyriphos and quinalphos was faster in 0.01 M CaCl-treated soil column. Among the pesticides analysed, the residue of quinalphos was detected in leachate.

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