The effect of intercropping with cowpea on genotype x environment interaction in sorghum.

Eight sorghum genotypes were grown at Hyderabad, India, in sole crop and in association with cowpea in six environments which differed in soil, season and sowing date . There were genotype x environment (G X E) interactions for sorghum yield and related variables, but the interaction was generally much smaller than the main effects . For each variable, the logarithm of the intercrop : sole crop ratio was generally less sensitive to the environment, but there was a significant G X E interaction for the logarithm of land equivalent ratio, indicating that the precise pattern of G x E effects differed between cropping systems . There was little evidence of G x E effects on cowpea, indicating that the effects of a sorghum genotype on the associated legume will be relatively simple to assess . The total LER was above 1 in most cases, indicating that intercropping gives a yield advantage over a wide range of environments and sorghum genotypes