Abstract. Aerosol black carbon (BC) mass concentrations were continuously monitored over a period of 2 years (April 2010 to May 2012) from a high-altitude location Ooty in the Nilgiris Mountain range in southern India to characterize the distinct nature of absorbing aerosols and their seasonality. Despite being remote and sparsely inhabited, BC concentrations showed significant seasonality with higher values (∼ 0.96 ± 0.35 µg m −3 ) in summer (March to May), attributed to increased vertical transport of effluents in the upwind valley regions, which might have been confined to the surrounding valley regions within the very shallow winter boundary layer. The local atmospheric boundary layer (ABL) influence in summer was further modulated by the long-range transported aerosols from the eastern locations of Ooty. During monsoon (June-August), the concentrations were far reduced (∼ 0.23 ± 0.06 µg m −3 ) due to intense precipitation. Diurnal variations were found conspicuous mainly during summer season associated with local ABL. The spectral absorption coefficients (α abs ) depicted, in general, flatter distribution (mostly < 1.0 for more than 85 % of daily mean values), suggesting the relative dominance of fossil fuel combustion, though showed marginal seasonal change with higher values of α abs in summer.

Excess of cations such as sodium and anions like carbonate, bicarbonate and chloride present in irrigation water, increase soil pH, Electrical Conductivity (EC) and Exchangeable Sodium Percentage (ESP) affect the growth and yield of the crop. To realise these impacts two field experiments were conducted for poor quality irrigation water with different amendments. Field experiment (I) was conducted on sandy loam soil at Pandipalayam, TNPL, Tamil Nadu, India with treated paper mill effluent as irrigation source and experiment (II) was conducted on sandy clay loam soil at Vatamalaipalayam, Thudialur, Tamil Nadu, India with saline groundwater as irrigation source, in a split plot design, with three replications. Among the different amendment applications, pressmud @ 15 t ha -1 along with 50 % (Gypsum) the soil pH (the reduction of 1.33 % was observed under treated paper mill effluent irrigation and 1.25 % was observed under saline groundwater irrigation), registered low EC, soil organic carbon and available nutrients (N, P, and K) were also improved under poor quality irrigation water.

Raising levels of tropospheric ozone (O 3), acts as a secondary pollutant and greenhouse gas which is a silent threat as well as one of the biggest challenges for the decrease in agricultural production. The diurnal and seasonal variation characteristics of ambient ozone (O 3) and its precursor NOx was investigated by their continuous measurements at ISRO-Climate Change Observatory situated in a high altitude Western Ghats location of Ooty. The impact of ambient O 3 on the growth and yield characteristics of various potato genotypes were assessed by the calculated higher ozone exposure indices AOT40 and SUM60 than critical levels by showing "latent injury" in the form of yield reduction (4.56-25.5 %) in potato genotypes. The impact of three elevated O 3 levels (100, 150 and 200 ppb for 4 hd-1) on ten potato genotypes was done by fumigation under controlled open-top chamber during its critical stage namely the tuber initiation stage resulted that Kufri Surya proved to be moderately resistant by recording the highest yield. HOW TO CITE THIS ARTICLE : Suganthy, V.S. and Udayasoorian, C. (2016). Assessing the impact of ambient ozone (O 3) on the growth and yield of potato genotypes (Solanum tuberosum L.) by using exposure indices over the high altitude of western Ghats location in Southern India.

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