56 Agricultural Research and Prochicilvify 



dition, it reveals a diffusion pattern related to the increasing com- 

 plexity and also to the nature and extent of research investment 

 by different regions. Both of these patterns reveal themselves in 

 other crop-biological improvement sequences. The stages of 

 varietal development are designed, not to demarcate discrete pro- 

 cesses, but to classify and describe these patterns. Consider first 

 the pattern of increasing complexity. Stage 2 separates the native 

 or farmer-selected crop varieties from those discovered in the 

 specialized and systematic efforts made to produce new varieties. 

 Plant-breeding activity in a number of crops precedes that of 

 sugarcane, but even today many plant varieties, especially in the 

 tree crops, are predominantly native or "stage 1" varieties. 



The distinction between stage 2 and stage 3 is more arbitrary. 

 In sugarcane, the advances associated with interspecific hy- 

 bridization are readily identified, likewise, with hybrid maize. 

 Other cases are not as straightforward. The distinction is between 

 two levels of applied research. Interspecific hybridization repre- 

 sented a major advance in the understanding of plant genetics. It 

 could not have been achieved without the discovery of basic 

 scientific principles. 



Similarly, there are other cases where the role of science is evi- 

 dent. The recent advances in wheat and rice productivity can be 

 described as stage 3-type advances. Stage 4 technology is dis- 

 tinguished from the stage 3 advances in that a particular kind of 

 "inducement" becomes apparent in the diffusion process. That is, 

 given investment in research in countries and regions that differ 

 in terms of soil and climate conditions, new discoveries which are 

 clearly "induced" by or based upon prior discoveries have a high 

 probability of being made. This pattern is reflected in the recent 

 Green Revolution, stage 3 type wheat and rice varieties. Coun- 

 tries with significant research capability have now produced a 

 number of stage 4 varieties that are superior to the Mexican 

 wheats and the IRRI rices. 



Direct diffusion of varieties is related to the international pat- 

 tern of research capabilities. The widespread diffusion of stage 3 

 varieties was partially due to the fact that many producing coun- 

 tries were not really capable of varietal production during the 

 1930s. However, the adoption of stage 4 technology led to very 

 significant international investment. 



