The book entitled 'Bt and Non-Bt cotton hybrids: Nitrogen fertilizer effects.' Deals with the commercial importance of Cotton hybrids ( Gossypium spp.) and how the Nitrogen fertilizer effects the growth and yield of cotton varieties. Field testing of these transgenic cottons proved that Bt cotton hybrids are not only more productive but also profitable over traditional non-Bt cottons. Nitrogen is a major macro nutrient, It is an essential part of amino acids and nucleic acids which are building blocks of protein and thus are essential to all life on Earth. Two Bt hybrids studied (RCH 134 and RCH 317) were physiologically superior to non-Bt hybrid 'LHH 144' and the inbuilt bollworm resistance of Bt hybrids was the cause for this superiority. Performance of cotton was markedly improved by N fertilization up to 180 kg N/ha in terms of growth and yield attributes, yield and nutrient uptake. Bt hybrids can prove more productive under low or no N fertilization and thus are suitable for cultivation in soils with low available Nitrogen.