Review on physiological and ecological characteristics and agronomic regulatory pathways of intercropping to delay root-canopy senescence of crops

Intercropping has been widely used in arid and semi-arid regions because of its high yield, and stable productivity, and efficient utilization of resources. However, in recent years, the high yield of traditional intercropping is mainly attributed to the large amount of purchased resources such as water and fertilizer, plastic film, and mechanical power. It leads to the decline of cultivated land quality and the phenomenon of premature root-canopy senescence of intercrops is become increasing serious. So, the application of traditional intercropping faces major challenges in crop production. In this paper, the manifestations, occurrence mechanisms, and agronomic regulatory pathways of crop senescence were analyzed in detail. The physiological and ecological characteristics of intercropping to delay root-canopy senescence of crops are reviewed in this paper. The main agronomic regulatory pathways of intercropping to delay root-canopy senescence of crops are based on above- and blow-ground interactions, include collocation of crop varieties, spatial arrangement, water and fertilizer management, and tillage and mulch practices. Future research fields of intercropping to delay root-canopy senescence should focus on the aspects of selecting and breeding special varieties, application of molecular biology techniques, and developing or applying models to predict and evaluate root-canopy senescence process of intercrops. Comprehensive analysis and evaluation of different research results could provide a basis for enhancing intercropping delay root-canopy senescence through adopting innovative technologies for regulating physio-ecological characteristics of intercrops. This would provide support for the development and adoption of high-yield, efficient, and sustainable intercropping systems in arid and semi-arid areas with more people and less land, and abundant light and heat resources.