| This review focused on the concept and studying methods of root activity patterns and their applications in cropland scientific management.Root activity pattern reflects the contribution of different parts of a root system to the total amount of nutrients absorbed by plants,and is used to indicate the functional variation in root system.Accordingly,root activity pattern is different from pattern of active roots.This challenges the widely accepted hypotheses that nutrient/water uptake is closely related to relative root length density.32P soil-injection is by far the most widely used method of studying root activity patterns,while soil-water-depletion method is mainly focalized in arid and semiarid regions.Root activity pattern is a more accurate parameter than pattern of active roots in delineating the spatiotemporal distribution of soil water uptake by plant.It makes potential use of root activity patterns in simulating water transfer from soil to crops and facilitate water management in field situation.Root activity patterns of crops and their changes with time give important hints in several situations such as deciding the zones and periods of fertilizer placement,choosing the most appropriate crop combination and spacing them properly in mixed-cropping system for complementary exploitation of below-ground resources,selecting the plant species with safety-net or nutrient pump functions in agroforestry,deciding the planting geometry,etc.In addition,the paper suggests that further research should focus on the comparison of root activity patterns measured by using different isotopes,the establishment of database of root activity spatiotemporal patterns for the common crops,etc. |