Gupta, KaushalyaTulika2016-12-012016-12-012005http://krishikosh.egranth.ac.in/handle/1/88658Avena sativa L. cv. HJ-8 plants were raised in earthenware pots filled with 5 Kg sand and treated with requisite amounts of Cd (0, 1, 5, 10, 20 and 40 ppm), Cr (VI) (0.1, 0.2, 0.5, 1.0, 2.5 and 5.0 ppm), and Cd:Cr (5:0.1, 5:0.5, 5:1.0, 20:0.1, 20:0.5 and 20:1.0 ppm) respectively in form of CdCl2 and K2Cr2O7. Chlorosis and tip burning started to appear after 10 ppm Cd and 0.5 ppm Cr (VI). At 5 ppm Cr (VI), very reduced plant height and severe chlorosis was observed followed by delayed flowering at 40 ppm Cd and 2.5 ppm Cr (VI) with no inflorescence emergence at 5.0 ppm Cr (VI) application. All the morphological parameters under study showed stimulation at lower doses (upto 5 ppm Cd and 0.5 ppm Cr (VI)) and then inhibited with further rise in heavy metal ion concentration. The fresh weight attained maximum value at 100 DAS and then decreased at maturity. FW and DW also showed a similar trend with increasing heavy metal ion levels. Photosynthetic pigments increased by 40% at 5 ppm Cd and 20% at 0.2 ppm Cr (VI) at 100 DAS and then decreased with increasing levels of Cd and Cr (VI). Chlorophyll b was found to be more sensitive than chlorophyll a under heavy metal toxicity. EC and pH of leaf leachates was found to be similar for all treatments while slight decrease was observed at higher doses. Nitrogen and nitrate nitrogen content was maximum at 5 ppm Cd, 0.1 ppm Cr (VI) and 5:0.1 ppm Cd:Cr combinations. Maximum reduction in Na and K content was observed at 40 ppm Cd, 5 ppm Cr (VI) and 20:1.0 ppm (Cd:Cr) application. However, the stimulation at lower doses was also observed. Crude fibre content was maximum at maturity with maximum reduction of 10% at higher doses of Cd2+ and Cr6+ ions. Sugar content attained maximum value at 100 DAS. Stimulation at lower doses of Cd and Cr was observed for sugar content which was maximum at 5 ppm Cd (43, 25 and 69%), 0.1 ppm Cr (VI) (40,14 and 38%) and Cd:CrenThesis