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We isolated four cultures of chromate resistant, unicellular, non-motile green algae from disposal sites of the paper-pulp and electroplating industries. These algae were maintained in Tris-acetate-glycerophosphate medium containing 30 μM K 2 Cr 2 O 7 . The morphological features as well as analysis of the 500-bp fragment of 18S rDNA (NS 12 region) showed that these isolates belong to Chlorella spp. These isolates showed EC 50 values for chromate ranging from 60 to 125 μM. Uptake studies with radioactive 51 Cr(VI) showed that 10-19% of total radioactivity was intracellular, and 1-2% was bound to the cell wall. The rest of the activity remained in the medium, suggesting that resistance was not related to accumulation of Cr(VI) in the cells. Interestingly, when these isolates were grown in the presence of 30 μM of K 2 Cr 2 O 7 , a decrease in the Cr(VI) concentration in the medium was observed. Only live cells could deplete Cr(VI) from the supernatant, suggesting the presence of chromium reduction activity in these Chlorella isolates. Cr(VI) reduction activity of the cells of Chlorella was stimulated by light as well as by acetate and glycerophosphate. Treatment of Chlorella cells with 3-(3,4 dichlorophenyl),1,1dimethyl urea (DCMU) did not affect the Cr(VI) reduction. However, if the cells were treated with sodium azide, Cr(VI) reduction was severely affected. Though chromate resistance has been well documented in algae, the information on chromate reduction by algae is scant. This paper discusses the Cr(VI) reduction by Cr(VI) resistant Chlorella, which may find a use in the effective bioremediation of Cr(VI).

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A field experiment was carried out at the research farm of National Research Centre for Onion and Garlic, Manjari, Pune (Maharashtra), India during kharif season of 2004 and 2005 to find out the effect of application of zinc and iron and their different modes of applications on growth, yield, and quality of onion. There were 27 treatment combinations with Zn and Fe were applied either in the soil or as foliar spray with cow dung slurry/FYM/gibbrelic acid/amino acids/2,4-D to onion. Application of Zn significantly increased the bulb weight (73.9 g), bulb yield (45 t/ha) when applied with 2,4-D (3 ppm) as foliar spray. Zinc application significantly influenced the bulb quality and recorded the highest 'A' grade bulbs and the lowest poor quality 'C' grade bulbs when applied with 2,4-D (81.9%) as foliar spray. The maximum medium 'B' grade bulbs were obtained with the application of Fe with cow dung slurry (11.4%).