In another experiment four plant species - Sorghum , Crotalaria, Cyamopsis and Commelina - were fumigated as above but were studied at flowering and /or fruiting stages. In case of Jowar it was noticed that the dry matter-production of shoot and root as well as-the length of inflorescence, were affected more in plants fumigated at 30 days-old stage as compared to those of 15 and 45 day-old stages, at 9 pphm concentration of sulphur dioxide. Simila results were observed in case of Cyamopsis but not in Commelina and Crotalaria. The extent of damage caused to the plants was different at different ages and at different concentrations in all the species studied.

Effect of Ammonia

Another pollutant gas, Ammonia, was tested for its effect on plants. Plants were fumigated by this gas - at 50 ppm concentration for three hours in the perspex chamber. Leaf area damage and chlorophyll contents 24 hours after fumigation, and net primary production of plants 30 days after fumigation, were studied in addition to the effect on the germinability of seeds of the following species :

1. Abelmoschus esculentus var. Pusa Savni,
2. Trigonella foenum-graecum,
3. Cvamopsis tetragonaloba Var. Pusa Navbahar and
4. Crotalaria juncea.

The germination of seeds and the growth performance of the germinated seedlings was adversely affected due to this gas. The percentage germination reduced significantly in 24 hours after fumigation. Root and shoot lengths as studied on the 5th day were low in fumigated plants in all the species, except in Abelmoschus. where the effect was not very distinct. The 15 day-old plants were studied 2h hours after fumigation for leaf area damage and chlorophyll contents. Cyamopsis and Crotalaria exhibited visible symptoms of leaf injury as chlorosis. Chlorophyll contents were found to have been reduced in the fumigated plants as compared with those in the controls. Some of the fumigated plants were allowed to grow for 30 days when they were harvested for the growth performance studies. It was found that there was decrease in the shoot length, number of nodes and dry matter production in fumigated plants. The relative sensitivity of the plants as shown by dry matter production was as follows :

Trigonella > Crotalaria > Abelmoschus > Cyamopsis.

A Field Experiment

Many methods have been developed to monitor air quality in cities. Biological indicators are alternatives to chemical and engineering methods which are expensive and cumbersome. Shetye and Chaphekar (1976) tried leaves of plants to assess the gravitational dust fall in Bombay city. An experiment was set up to check if growth and yields of plants could be used as parameters for air quality indication. Four plant species - Helianthus annus L. var. Japanese dwarf, Commelina benghalensis, Cvamopsis tetragonaloba var. Pusa Navbahar and Crotalaria juncea, were grown under identical conditions of soil, water and exposure and then distributed at ten spots across the city. These were harvested after four weeks of exposure to the ambient air at those spots. The differences encountered in the plants in terms of standing phytomass, chlorophyll and protein contents, shoot length, etc., were related to the known air quality conditions.

The length and dry matter production of shoot were found to be reliable parameters of air quality. Higher dry matter production and shoot length, were observed in clean area as compared, to those in polluted areas. Cyamopsis was found to be more sensitive to quality of the ambient air as indicated by shoot length, number, of pods per plant, length, of pod, length of the 4th internode from the top and dry matter production. The chapter end with a discussion on the possibility of using plants for air monitoring in urban areas.

The last chapter of the thesis deals with the subject of the impact of air pollution on plant production using the work presented here as thebasis. Conclusions and summary of the work are given towards the end of the thesis.

Literature cited
Bandyopadhyaya A. K.	1976	Plants and Pollution: M. Se. Thesis to the    University of Bombay.
Brandt, C. C. and Heck, W. W.	1968	Effects of pollutants on vegetation in AIR POLLUTION, 2nd Ed. Vol.-I.pp.401- 443  A. C. Stern (ed.), Academic Press, New York
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Shetye R. P. and Chaphekar, S. B.	1976	An inexpensive method for the determination   of air borne dusts. Proc. Seminar on "Man and His Environment", Dec.'76, pp. 85-88.
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