Response of interspecific competition and complementarity of maize/pea intercropping to reduced tillage and high-density planting

Through the study of an interspecific relationship, the effects of reduced tillage and high-density planting was analyzed in a maize/pea intercropping system. The research could provide a theoretical basis for further optimization of intercropping technology. The study, conducted in 2016-2017 in the Hexi Oasis Irrigation Area, used a maize/pea intercropping system as the research setup. Two tillage patterns were measured:conventional tillage and reduced tillage. Simultaneously, maize was planted at low, medium and high density to study the effects of different treatments on the competitiveness of maize/pea intercropping systems. Also, the recovery ability of maize after the pea harvest was analyzed to reveal the interspecies relationship and the correlation with intercropping production. The results showed that the land equivalent ratio of different intercropping treatments was higher than 1, indicating that these intercropping treatments resulted in an increased yield. Compared with conventional tillage, reduced tillage increased the yield of maize/pea intercropping system by 5.79%. Under reduced tillage conditions, the yield of intercropping system at medium density was considerably increased by 8.37% and 9.09% relative to low-density and high-density conditions, respectively. This observation indicates that combining reduced tillage with a medium-density plantation further increased the yield of a maize/pea intercropping system. Reduced tillage combined with a medium-density plantation enhanced the competitiveness of maize/pea intercropping:the competitiveness was 36.56% and 20.17% higher relative to the low-density and high-density treatment, respectively. The enhanced competitiveness formed the basis of the enhanced maize intercropping recovery effect. After the pea harvest under reduced tillage conditions, maize displayed a significant recovery growth effect, which was 10.30%-47.11% higher than that under conventional tillage conditions. The correlation between the grain yields of intercropping system and the average competitiveness of pea relative to maize during the whole growth period was quadratic function. The integration of reduced tillage and a medium-density planting technology in the maize/pea intercropping model provides the potential for an intercropping system to increase the yield by regulating the interspecific relationship.