Redefining cotton growing zones in India for effective product and technology placement

Cotton is an important commercial crop of India which is cultivated in diverse pedo-climatic conditions across the cotton growing regions. Of the 20 agro-eco regions (AERs) with 60 agro-eco sub-regions (AESRs), major cotton districts in India falls into 26 AESRs across 11 AERs. The dominant AERs supporting cotton are 6, 5, 7 and 2 which accounts to 83% of India's cotton. There is large variation in cotton yields across different AESRs, ranging from 149 kg/ha in AESR 8.1 to 764 kg/ha in AESR 12.2. The new varieties/hybrids are often developed and further evaluated in an environment which is dissimilar to the farmers’ fields, the ultimate target environments. The soil and climatic features of the target environment is very important for the plant breeders to develop suitable varieties and hybrids in line with the available moisture capacity and length of growing period for realizing potential yields in a given AESR. The enormous pedo-climatic diversity creates a wide spatial disparity in cotton yields. The pedo-climatic conditions across cotton growing regions and presently cultivated cotton hybrids/varieties are not in sync. Often, the production technologies adopted are also not based on the pedo-climate opportunities and constraints. With enormous diversity in pedoclimatic factors at testing locations in India for cotton, there is a greater need to delineate the existing cotton growing zones for more meaningful and relevant interpretations for efficient and effective product and technology placement. The AER/AESR concept presented in this chapter could provide a more rational and relevant way of delineating cotton recommendations based on pedo-climatic homogeneity. Cotton product profiles and technologies could also be conceptualized in view of the constraints and opportunities offered by each AERs/AESRs for enhanced cotton productivity in India