ABSTRACT
I. BACKGROUND Asia covers about one fourth of the globe's land mass and accommodates over 60% of the world's population. It constitutes one quarter of the agricultural area and 36% of arable land of the world. The continent produces 43% of the total wheat of the world and shares over 90% of total rice production (Gill, 1999). Nature has blessed the region with abundant agricultural and manpower resources and a favorable climate. The diversity in natural resources, climate, people, and socioeconomic conditions has given rise to diverse farming systems in the region. The Green Revolution technologies introduced in this region during the mid1960s and 1970s led to a dramatic increase in yields and production of wheat and rice, the two most important staple food grains in this region. These crops occupy 54% of the total world's area planted to cereals and provide 41 % of the calories consumed by over six billion people around the globe. In the first decade of the Green Revolution, grain production grew rapidly, mainly due to adoption of high-yielding varieties (HYV), increased use of fertilizers, irrigation, and cropping intensity (two crops instead of one), and increased cropped area. Since then the land devoted to rice and wheat has stabilized and there is very little scope for further expansion in area for these crops.
