Abstract: The ecological mechanism of competition and compensation between the crop root systems of two different intercropping patterns, wheat-soybean and corn-cabbage, was studied by field experiment. The results showed that the annual growth peak of wheat soybean roots in intercropping was interlacing, the growth of root weight and length expressed synchronism, and the peak of root weight was appeared earlier than that of root length. The vertical distribution of the two crops' root system in two intercroppings was reduced gradually along with soil depths, which also showed that the multiple growth waves moved progressively. The root system distributed horizontally in intercropping system also showed a clearly unbalanced distribution. The root system distribution of out row for corn elongated 20.4～40.8 cm to cabbage rows, but that of cabbage elongated only 8.5～12.6 cm to corn. The cross extent of root systems in corn cabbage intercropping was decreased from 40.2 cm to 20.1 cm by fertilization, and the place of cross point for root concentrated region was changed from 20.5 cm to 12.4 cm below soil surface by fertilizer supply. The place of cross point for root concentrated region was an important index to decide the degrees of competition.

Key words: Intercropping, Root system, Wheat-soybean intercropping, Corn cabbage intercropping