EFFECT OF CADMIUM AND NICKEL ON GERMINATION, EARLY SEEDLING GROWTH AND PHOTOSYNTHESIS OF WHEAT AND PIGEONPEA

The experiments were conducted in petri dishes and sand culture to study the effect of different concs. of Cd and Ni on germination, early seedling growth and dry matter production of wheat and pigeonpea. In petri dishes, the germination of wheat was decreased by 60 per cent at a solution conc. of 4 mM of chloride salts of both the metals, whereas at this conc. the germination of pigeonpea was affected by 85 per cent by Cd and 25 per cent by Ni. In sand culture experiments, the results on relative sensitivity of these crops were similar, but the toxicity of metals decreased considerably. Even at a conc. of 40 mg/kg sand of both the metals (equivalent to 4mM conc. in petri dishes), wheat germination was 100 per cent. However, in sand culture also, the higher concentrations of these metals suppressed the emergence of radicle. In both the crops, the development of radicle was more sensitive than the growth of plumule/coleoptile to both the metals, Cd being more toxic than Ni. The dry matter production, leal area and photosynthesis were affected less in wheat than in pigeonpea by both the metals. In pigeonpea, Cd was more toxic than Ni. The overall results show that wheat was more tolerant than pigeonpea and Cd more toxic than Ni, and the toxicity of merals was less in culture than in sand solution culture.