1. Dep. of Agronomy; Punjab Agricultural Univ.; Ludhiana India
2. Crop, Soil, and Water Science Division; International Rice Research Institute (IRRI); DAPO 7777 Metro Manila Philippines
3. Social Sciences Division; International Rice Research Institute (IRRI); DAPO 7777 Metro Manila Philippines
4. Rice-Wheat Consortium for Indo-Gangetic Plains; NASC Complex, Pusa New Delhi 110 012 India