Lead Stress Effects on Physiobiochemical Activities of Higher Plants Rakesh Singh Sengar, Madhu Gautam, Rajesh Singh Sengar , Sanjay Kumar Garg, Kalpana Sengar, and Reshu Chaudhary Contents 1 Introduction ........................................................................................................................ 73 2 Sources of Lead Pollution .................................................................................................. 75 3 Behavior of Lead in Plants and Effects on Plant Processes ............................................... 76 3.1 Foliar Deposition of Lead ......................................................................................... 76 3.2 Lead Uptake by Plants .............................................................................................. 76 3.3 Localization and Levels of Lead in Plant Parts......................................................... 77 3.4 Seed Germination and Seedling Growth................................................................... 80 3.5 Plant Growth and Productivity.................................................................................. 80 3.6 Effects on Photosynthesis ......................................................................................... 81 3.7 Effects on Respiration ............................................................................................... 84 3.8 Effects on Nitrogen Assimilation.............................................................................. 85 3.9 Pigment Control ........................................................................................................ 86 4 Summary ............................................................................................................................ 86 References ............................................................................................................................... 87 D.M. Whitacre (ed.) Reviews of Environmental Contamination and Toxicology, Vol 196, 73 doi: 10.1007/978-0-387-78444-1_3, © Springer Science + Business Media, LLC 2008 M. Gautam Institute of Management Studies, C-238, Bulandshahr Road, Indl, Area, Lal Quan, G.T. Road, Ghaziabad, India R.S. Sengar, K. Sengar, R. Chaudhary College of Biotechnology, Sardar Vallabh Bhai Patel University of Agriculture and Technology, Meerut, India S.K. Garg Department of Plant Science, M.J.P. Rohillkhand University Bareilly , India R.J. Sengar, R.S. Sengar Meerut Institute of Engineering and Technology, Partapur Bypass, Meerut, India 1 Introduction Environmental degradation caused by rapid industrial expansion of activities such as mining, power generation, transportation, and intensive agriculture, among others, has become a major threat to the sustenance and welfare of mankind. During the past