Effect of intercropping on maize grain yield and yield components

Smallholders in developing countries commonly use intercropping to produce crops with higher yield and value. Many intercropping studies have been conducted under experimental conditions, but few studies have been performed in farmers' fields. We conducted a 4-year study using data from real farms to examine the relationships between yield and yield components of intercropped maize in the North China Plain. Three field experiments were conducted to compare the suitability of different maize varieties in intercropping. In the farm study, the grain yield of maize intercropped with watermelon was reduced by more than one third as compared to maize in wheat-maize double cropping, mainly due to lower ear density and lower 100-grain weight. Under real farm conditions, the yield of intercropped maize increased with increasing ear density and 100-grain weight, while yield of sole maize increased with increasing grain number per ear and 100-grain weight. In the field experiments, the maize cultivars commonly used in double cropping gave similar yields when grown in the intercropping system and their yields were closely related to ear density and 100-grain weight. Our results demonstrated that ear density, rather cultivar, was a key factor affecting the productivity of intercropped maize. Therefore,maintaining high ear density is a practical way for promoting productivity of maize in farmers' intercropping practices.